...the scientific cast of mind examines the world critically, as if many alternative worlds might exist, as if other things might be here which are not. Then we are forced to ask why what we see is present and not something else. Why are the Sun and moon and the planets spheres? Why not pyramids, or cubes, or dodecahedra? Why not irregular, jumbly shapes? Why so symmetrical, worlds? If you spend any time spinning hypotheses, checking to see whether they make sense, whether they conform to what else we know. Thinking of tests you can pose to substantiate or deflate hypotheses, you will find yourself doing science.

“I think you’re begging the question,” said Haydock, “and I can see looming ahead one of those terrible exercises in probability where six men have white hats and six men have black hats and you have to work it out by mathematics how likely it is that the hats will get mixed up and in what proportion. If you start thinking about things like that, you would go round the bend. Let me assure you of that!”

“There is no expedient to which a man will not resort to avoid the real labor of thinking.
Sir Joshua Reynolds.”

“Thinking again?” the Duchess asked, with another dig of her sharp little chin. “I’ve a right to think,” said Alice sharply, for she was beginning to feel a little worried. “Just about as much right,” said the Duchess, “as pigs have to fly.”

[1665-12-31] Thus ends this year ... It is true we have gone through great melancholy because of the great plague, and I put to great charges by it, by keeping my family long at Woolwich, and myself and another part of my family, my clerks, at my charge at Greenwich ... But now the plague is abated almost to nothing ... But many of such as I know very well, dead. Yet to our great joy, the town fills apace, and shops begin to open again. Pray God continue the plague's decrease - for that keeps the Court away from the place of business, and so all goes to wrack as to public matters, they at this distance not thinking of it.

[A crowd] thinks in images, and the image itself calls up a series of other images, having no logical connection with the first … A crowd scarcely distinguishes between the subjective and the objective. It accepts as real the images invoked in its mind, though they most often have only a very distant relation with the observed facts. * * * Crowds being only capable of thinking in images are only to be impressed by images. It is only images that terrify or attract them and become motives of action.

[Consider] a fence or gate erected across a road] The more modern type of reformer goes gaily up to it and says, “I don't see the use of this; let us clear it away.” To which the more intelligent type of reformer will do well to answer: “If you don't see the use of it, I certainly won't let you clear it away. Go away and think. Then, when you can come back and tell me that you do see the use of it, I may allow you to destroy it.”

[D]iscovery should come as an adventure rather than as the result of a logical process of thought. Sharp, prolonged thinking is necessary that we may keep on the chosen road but it does not itself necessarily lead to discovery. The investigator must be ready and on the spot when the light comes from whatever direction.

[For corporate computing centers:] Probably the biggest threat is people thinking that they can buy broken things and then put patches on afterward and make it secure.

[I attach] little importance to physical size. I don’t feel the least humble before the vastness of the heavens. The stars may be large, but they cannot think or love; and these are qualities which impress me far more than size does.

[It] is not the nature of things for any one man to make a sudden, violent discovery; science goes step by step and every man depends on the work of his predecessors. When you hear of a sudden unexpected discovery—a bolt from the blue—you can always be sure that it has grown up by the influence of one man or another, and it is the mutual influence which makes the enormous possibility of scientific advance. Scientists are not dependent on the ideas of a single man, but on the combined wisdom of thousands of men, all thinking of the same problem and each doing his little bit to add to the great structure of knowledge which is gradually being erected.

[Learning is] the actual process of broadening yourself, of knowing there’s a little extra facet of the universe you know about and can think about and can understand. It seems to me that when it’s time to die, and that will come to all of us, there’ll be a certain pleasure in thinking that you had utilized your life well, that you had learned as much as you could, gathered in as much as possible of the universe, and enjoyed it. I mean, there’s only this universe and only this one lifetime to try to grasp it. And, while it is inconceivable that anyone can grasp more than a tiny portion of it, at least do that much. What a tragedy to just pass through and get nothing out of it.

[Public cynicism towards professional expertise is] entirely wrong, and it’s the road back to the cave. The way we got out of the caves and into modern civilisation is through the process of understanding and thinking. Those things were not done by gut instinct. Being an expert does not mean that you are someone with a vested interest in something; it means you spend your life studying something. You’re not necessarily right–but you’re more likely to be right than someone who’s not spent their life studying it.

[Resist the temptation to] work so hard that there is no time left for serious thinking …[Scientists] should heed the saying, “A busy life is a wasted life.”

[Science] is not a job nine to five. When you do science you have to do science 24 hours a day. When you are at home you should be thinking about science; when you are going to bed, you should be dreaming about science. It’s full immersion vou see.

[There] are cases where there is no dishonesty involved but where people are tricked into false results by a lack of understanding about what human beings can do to themselves in the way of being led astray by subjective effects, wishful thinking or threshold interactions. These are examples of pathological science. These are things that attracted a great deal of attention. Usually hundreds of papers have been published upon them. Sometimes they have lasted for fifteen or twenty years and then they gradually die away.
[Coining the term “pathological science” for the self-deceiving application of science to a phenomenon that doesn't exist.]

[To a man expecting a scientific proof of the impossibility of flying saucers] I might have said to him: “Listen, I mean that from my knowledge of the world that I see around me, I think that it is much more likely that the reports of flying saucers are the results of the known irrational characteristics of terrestrial intelligence than of the unknown rational efforts of extra-terrestrial intelligence.” It is just more likely, that is all. It is a good guess. And we always try to guess the most likely explanation, keeping in the back of the mind the fact that if it does not work we must discuss the other possibilities.

[When thinking about the new relativity and quantum theories] I have felt a homesickness for the paths of physical science where there are more or less discernible handrails to keep us from the worst morasses of foolishness.

[Elementary student, laying a cocoon on the teacher's desk:] That is serendipity. The caterpillar thinks it is dying but it is really being born.

[Question: What do you think was the most important physics idea to emerge this year?]
We won't know for a few years.

Alles Gescheite ist schon gedacht worden; man muss nur versuchen, es noch einmal zu denken.
Everything that is worth thinking has already been thought; one must only try to think it again.

Dilbert: Wow! According to my computer simulation, it should be possible to create new life forms from common household chemicals
Dogbert: This raises some thorny issues.
Dilbert: You mean legal, ethical and religious issues?
Dogbert: I was thinking about parking spaces.

Dilbert: I’m obsessed with inventing a perpetual motion machine. Most scientists think it's impossible, but I have something they don’t.
Dogbert: A lot of spare time?
Dilbert: Exactly.

Douter de tout ou tout croire, ce sont deux solutions également commodes, qui l’une et l’autre nous dispensent de défléchir.
To doubt everything and to believe everything are two equally convenient solutions; each saves us from thinking.

L’homme n’est qu’un roseau, le plus faible de la nature; mais c’est un roseau pensant.
Man is but a reed, the weakest thing in nature; but a thinking reed.

Non cogitant, ergo non sunt.
[They do not think, therefore they are not.]

Ohne Phosphor, Kein Gedanke.
Without phosphorus there would be no thought.
[This is wrongly attributed to Büchner.]

Rassemblons des faits pour nous donner des idées.
Let us gather facts in order to get ourselves thinking.

Ratbert (as lab rat, to scientist): Doc, we have to talk. Every day you feed me over a hundred pounds of macaroni and cheese. At first I thought you were just being a good host. But lately I’ve been thinking it could be something far more sinister.
Scientist (thinking): Macaroni and cheese causes paranoia.

~~[Attributed]~~ A great many people think they are thinking when they are merely rearranging their prejudices.

~~[Misattributed?]~~ Just remember—when you think all is lost, the future remains.

~~[Reinterpretation]~~ The significant problems we face cannot be solved at the same level of thinking we were at when we created them.

A conclusion is the place where you got tired thinking.

A designer must always think about the unfortunate production engineer who will have to manufacture what you have designed; try to understand his problems.

A good theoretical physicist today might find it useful to have a wide range of physical viewpoints and mathematical expressions of the same theory (for example, of quantum electrodynamics) available to him. This may be asking too much of one man. Then new students should as a class have this. If every individual student follows the same current fashion in expressing and thinking about electrodynamics or field theory, then the variety of hypotheses being generated to understand strong interactions, say, is limited. Perhaps rightly so, for possibly the chance is high that the truth lies in the fashionable direction. But, on the off-chance that it is in another direction—a direction obvious from an unfashionable view of field theory—who will find it?

A lot of people ask, “Do you think humans are parasites?” It’s an interesting idea and one worth thinking about. People casually refer to humanity as a virus spreading across the earth. In fact, we do look like some strange kind of bio-film spreading across the landscape. A good metaphor? If the biosphere is our host, we do use it up for our own benefit. We do manipulate it. We alter the flows and fluxes of elements like carbon and nitrogen to benefit ourselves—often at the expense of the biosphere as a whole. If you look at how coral reefs or tropical forests are faring these days, you’ll notice that our host is not doing that well right now. Parasites are very sophisticated; parasites are highly evolved; parasites are very successful, as reflected in their diversity. Humans are not very good parasites. Successful parasites do a very good job of balancing—using up their hosts and keeping them alive. It’s all a question of tuning the adaptation to your particular host. In our case, we have only one host, so we have to be particularly careful.

A mathematician’s work is mostly a tangle of guesswork, analogy, wishful thinking and frustration, and proof, far from being the core of discovery, is more often than not a way of making sure that our minds are not playing tricks.

A multidisciplinary study group ... estimated that it would be 1980 before developments in artificial intelligence make it possible for machines alone to do much thinking or problem solving of military significance. That would leave, say, five years to develop man-computer symbiosis and 15 years to use it. The 15 may be 10 or 500, but those years should be intellectually the most creative and exciting in the history of mankind.

A parable: A man was examining the construction of a cathedral. He asked a stone mason what he was doing chipping the stones, and the mason replied, “I am making stones.” He asked a stone carver what he was doing. “I am carving a gargoyle.” And so it went, each person said in detail what they were doing. Finally he came to an old woman who was sweeping the ground. She said. “I am helping build a cathedral.”
...Most of the time each person is immersed in the details of one special part of the whole and does not think of how what they are doing relates to the larger picture.
[For example, in education, a teacher might say in the next class he was going to “explain Young's modulus and how to measure it,” rather than, “I am going to educate the students and prepare them for their future careers.”]

A quarter-horse jockey learns to think of a twenty-second race as if it were occurring across twenty minutes—in distinct parts, spaced in his consciousness. Each nuance of the ride comes to him as he builds his race. If you can do the opposite with deep time, living in it and thinking in it until the large numbers settle into place, you can sense how swiftly the initial earth packed itself together, how swiftly continents have assembled and come apart, how far and rapidly continents travel, how quickly mountains rise and how quickly they disintegrate and disappear.

A teacher of mathematics has a great opportunity. If he fills his allotted time with drilling his students in routine operations he kills their interest, hampers their intellectual development, and misuses his opportunity. But if he challenges the curiosity of his students by setting them problems proportionate to their knowledge, and helps them to solve their problems with stimulating questions, he may give them a taste for, and some means of, independent thinking.

About 85 per cent of my “thinking” time was spent getting into a position to think, to make a decision, to learn something I needed to know. Much more time went into finding or obtaining information than into digesting it. Hours went into the plotting of graphs... When the graphs were finished, the relations were obvious at once, but the plotting had to be done in order to make them so.

Accuracy of observation is the equivalent of accuracy of thinking.

Across the road from my cabin was a huge clear-cut—hundreds of acres of massive spruce stumps interspersed with tiny Douglas firs—products of what they call “Reforestation,” which I guess makes the spindly firs en masse a “Reforest,” which makes an individual spindly fir a “Refir,” which means you could say that Weyerhauser, who owns the joint, has Refir Madness, since they think that sawing down 200-foot-tall spruces and replacing them with puling 2-foot Refirs is no different from farming beans or corn or alfalfa. They even call the towering spires they wipe from the Earth’s face forever a “crop”--as if they’d planted the virgin forest! But I'm just a fisherman and may be missing some deeper significance in their nomenclature and stranger treatment of primordial trees.

Again and again in reading even his [William Thomson] most abstract writings one is struck by the tenacity with which physical ideas control in him the mathematical form in which he expressed them. An instance of this is afforded by … an example of a mathematical result that is, in his own words, “not instantly obvious from the analytical form of my solution, but which we immediately see must be the case by thinking of the physical meaning of the result.”

All great discoveries are made by men whose feelings run ahead of their thinking.

All interpretations made by a scientist are hypotheses, and all hypotheses are tentative. They must forever be tested and they must be revised if found to be unsatisfactory. Hence, a change of mind in a scientist, and particularly in a great scientist, is not only not a sign of weakness but rather evidence for continuing attention to the respective problem and an ability to test the hypothesis again and again.

All that can accurately be said about a man who thinks he is a poached egg is that he is in the minority.

All the different classes of beings which taken together make up the universe are, in the ideas of God who knows distinctly their essential gradations, only so many ordinates of a single curve so closely united that it would be impossible to place others between any two of them, since that would imply disorder and imperfection. Thus men are linked with the animals, these with the plants and these with the fossils which in turn merge with those bodies which our senses and our imagination represent to us as absolutely inanimate. And, since the law of continuity requires that when the essential attributes of one being approximate those of another all the properties of the one must likewise gradually approximate those of the other, it is necessary that all the orders of natural beings form but a single chain, in which the various classes, like so many rings, are so closely linked one to another that it is impossible for the senses or the imagination to determine precisely the point at which one ends and the next begins?all the species which, so to say, lie near the borderlands being equivocal, at endowed with characters which might equally well be assigned to either of the neighboring species. Thus there is nothing monstrous in the existence zoophytes, or plant-animals, as Budaeus calls them; on the contrary, it is wholly in keeping with the order of nature that they should exist. And so great is the force of the principle of continuity, to my thinking, that not only should I not be surprised to hear that such beings had been discovered?creatures which in some of their properties, such as nutrition or reproduction, might pass equally well for animals or for plants, and which thus overturn the current laws based upon the supposition of a perfect and absolute separation of the different orders of coexistent beings which fill the universe;?not only, I say, should I not be surprised to hear that they had been discovered, but, in fact, I am convinced that there must be such creatures, and that natural history will perhaps some day become acquainted with them, when it has further studied that infinity of living things whose small size conceals them for ordinary observation and which are hidden in the bowels of the earth and the depth of the sea.

All the modern higher mathematics is based on a calculus of operations, on laws of thought. All mathematics, from the first, was so in reality; but the evolvers of the modern higher calculus have known that it is so. Therefore elementary teachers who, at the present day, persist in thinking about algebra and arithmetic as dealing with laws of number, and about geometry as dealing with laws of surface and solid content, are doing the best that in them lies to put their pupils on the wrong track for reaching in the future any true understanding of the higher algebras. Algebras deal not with laws of number, but with such laws of the human thinking machinery as have been discovered in the course of investigations on numbers. Plane geometry deals with such laws of thought as were discovered by men intent on finding out how to measure surface; and solid geometry with such additional laws of thought as were discovered when men began to extend geometry into three dimensions.

All you really need to know for the moment is that the universe is a lot more complicated than you might think, even if you start from a position of thinking it’s pretty damn complicated in the first place.

Almost all the world is natural chemicals, so it really makes you re-think everything. A cup of coffee is filled with chemicals. They've identified a thousand chemicals in a cup of coffee. But we only found 22 that have been tested in animal cancer tests out of this thousand. And of those, 17 are carcinogens. There are ten milligrams of known carcinogens in a cup of coffee and thats more carcinogens than youre likely to get from pesticide residues for a year!

Amazing that the human race has taken enough time out from thinking about food or sex to create the arts and sciences.

Analogy is a wonderful, useful and most important form of thinking, and biology is saturated with it. Nothing is worse than a horrible mass of undigested facts, and facts are indigestible unless there is some rhyme or reason to them. The physicist, with his facts, seeks reason; the biologist seeks something very much like rhyme, and rhyme is a kind of analogy.... This analogizing, this fine sweeping ability to see likenesses in the midst of differences is the great glory of biology, but biologists don't know it.... They have always been so fascinated and overawed by the superior prestige of exact physical science that they feel they have to imitate it.... In its central content, biology is not accurate thinking, but accurate observation and imaginative thinking, with great sweeping generalizations.

And as I had my father’s kind of mind—which was also his mother’s—I learned that the mind is not sex-typed.

And now, as a germination of planetary dimensions, comes the thinking layer which over its full extent develops and intertwines its fibres, not to confuse and neutralise them but to reinforce them in the living unity of a single tissue.

Another argument of hope may be drawn from this–that some of the inventions already known are such as before they were discovered it could hardly have entered any man's head to think of; they would have been simply set aside as impossible. For in conjecturing what may be men set before them the example of what has been, and divine of the new with an imagination preoccupied and colored by the old; which way of forming opinions is very fallacious, for streams that are drawn from the springheads of nature do not always run in the old channels.

Another characteristic of mathematical thought is that it can have no success where it cannot generalize.

Antiessentialist thinking forces us to view the world differently. We must accept shadings and continua as fundamental. We lose criteria for judgment by comparison to some ideal: short people, retarded people, people of other beliefs, colors, and religions are people of full status.

Anton Chekhov wrote that ‘one must not put a loaded rifle on stage if no one is thinking of firing it.’ Good drama requires spare and purposive action, sensible linking of potential causes with realized effects. Life is much messier; nothing happens most of the time. Millions of Americans (many hotheaded) own rifles (many loaded), but the great majority, thank God, do not go off most of the time. We spend most of real life waiting for Godot, not charging once more unto the breach.

Anyone who thinks science is trying to make human life easier or more pleasant is utterly mistaken.

Artificial intelligence is based on the assumption that the mind can be described as some kind of formal system manipulating symbols that stand for things in the world. Thus it doesn't matter what the brain is made of, or what it uses for tokens in the great game of thinking. Using an equivalent set of tokens and rules, we can do thinking with a digital computer, just as we can play chess using cups, salt and pepper shakers, knives, forks, and spoons. Using the right software, one system (the mind) can be mapped onto the other (the computer).

As agonizing a disease as cancer is, I do not think it can be said that our civilization is threatened by it. … But a very plausible case can be made that our civilization is fundamentally threatened by the lack of adequate fertility control. Exponential increases of population will dominate any arithmetic increases, even those brought about by heroic technological initiatives, in the availability of food and resources, as Malthus long ago realized.

As followers of natural science we know nothing of any relation between thoughts and the brain, except as a gross correlation in time and space.

As modern physics started with the Newtonian revolution, so modern philosophy starts with what one might call the Cartesian Catastrophe. The catastrophe consisted in the splitting up of the world into the realms of matter and mind, and the identification of “mind” with conscious thinking. The result of this identification was the shallow rationalism of l’esprit Cartesien, and an impoverishment of psychology which it took three centuries to remedy even in part.

As regards religion, on the other hand, one is generally agreed that it deals with goals and evaluations and, in general, with the emotional foundation of human thinking and acting, as far as these are not predetermined by the inalterable hereditary disposition of the human species. Religion is concerned with man’s attitude toward nature at large, with the establishing of ideals for the individual and communal life, and with mutual human relationship. These ideals religion attempts to attain by exerting an educational influence on tradition and through the development and promulgation of certain easily accessible thoughts and narratives (epics and myths) which are apt to influence evaluation and action along the lines of the accepted ideals.

Astronomers and physicists, dealing habitually with objects and quantities far beyond the reach of the senses, even with the aid of the most powerful aids that ingenuity has been able to devise, tend almost inevitably to fall into the ways of thinking of men dealing with objects and quantities that do not exist at all, e.g., theologians and metaphysicians. Thus their speculations tend almost inevitably to depart from the field of true science, which is that of precise observation, and to become mere soaring in the empyrean. The process works backward, too. That is to say, their reports of what they pretend actually to see are often very unreliable. It is thus no wonder that, of all men of science, they are the most given to flirting with theology. Nor is it remarkable that, in the popular belief, most astronomers end by losing their minds.

Astronomy was thus the cradle of the natural sciences and the starting point of geometrical theories. The stars themselves gave rise to the concept of a ‘point’; triangles, quadrangles and other geometrical figures appeared in the constellations; the circle was realized by the disc of the sun and the moon. Thus in an essentially intuitive fashion the elements of geometrical thinking came into existence.

At present we must confine ourselves to saying that soul is the source of these phenomena and is characterized by them, viz. by the powers of self-nutrition, sensation, thinking, and movement.

Behold the mighty dinosaur,
Famous in prehistoric lore,
Not only for his power and strength
But for his intellectual length.
You will observe by these remains
The creature had two sets of brains—
One in his head (the usual place),
The other at his spinal base.
Thus he could reason 'A priori'
As well as 'A posteriori'.
No problem bothered him a bit
He made both head and tail of it.
So wise was he, so wise and solemn,
Each thought filled just a spinal column.
If one brain found the pressure strong
It passed a few ideas along.
If something slipped his forward mind
'Twas rescued by the one behind.
And if in error he was caught
He had a saving afterthought.
As he thought twice before he spoke
He had no judgment to revoke.
Thus he could think without congestion
Upon both sides of every question.
Oh, gaze upon this model beast
Defunct ten million years at least.

Bohr’s standpoint, that a space-time description is impossible, I reject a limine. Physics does not consist only of atomic research, science does not consist only of physics, and life does not consist only of science. The aim of atomic research is to fit our empirical knowledge concerning it into our other thinking. All of this other thinking, so far as it concerns the outer world, is active in space and time. If it cannot be fitted into space and time, then it fails in its whole aim and one does not know what purpose it really serves.

But by far the greatest obstacle to the progress of science and to the undertaking of new tasks and provinces therein is found in this—that men despair and think things impossible.

But if you have seen the soil of India with your own eyes and meditate on its nature - if you consider the rounded stones found in the earth however deeply you dig, stones that are huge near the mountains and where the rivers have a violent current; stones that are of smaller size at greater distance from the mountains, and where the streams flow more slowly; stones that appear pulverised in the shape of sand where the streams begin to stagnate near their mouths and near the sea - if you consider all this, you could scarcely help thinking that India has once been a sea which by degrees has been filled up by the alluvium of the streams.

But the real glory of science is that we can find a way of thinking such that the law is evident.

Careful and correct use of language is a powerful aid to straight thinking, for putting into words precisely what we mean necessitates getting our own minds quite clear on what we mean.

Children are told that an apple fell on Isaac Newton’s head and he was led to state the law of gravity. This, of course, is pure foolishness. What Newton discovered was that any two particles in the universe attract each other with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them. This is not learned from a falling apple, but by observing quantities of data and developing a mathematical theory that can be verified by additional data. Data gathered by Galileo on falling bodies and by Johannes Kepler on motions of the planets were invaluable aids to Newton. Unfortunately, such false impressions about science are not universally outgrown like the Santa Claus myth, and some people who don’t study much science go to their graves thinking that the human race took until the mid-seventeenth century to notice that objects fall.

D’you know how embarrassing it is to mention good and evil in a scientific laboratory? Have you any idea? One of the reasons l became a scientist was not to have to think about that kind of thing.

Discovery consists of seeing what everybody has seen and thinking what nobody has thought.

Do not say hypothesis, and even less theory: say way of thinking.

Doctors coin money when they do procedures—family practice doesn’t have any procedures. A urologist has cystoscopies, a gastroenterologist has gastroscopies, a dermatologist has biopsies. They can do three or four of those and make five or six hundred dollars in a single day. We get nothing for the use of our time to understand the lives of our patients. Technology is rewarded in medicine, it seems to me, and not thinking.

During my eighty-seven years I have witnessed a whole succession of technological revolutions. But none of them has done away with the need for character in the individual or the ability to think.

During the time that [Karl] Landsteiner gave me an education in the field of imununology, I discovered that he and I were thinking about the serologic problem in very different ways. He would ask, What do these experiments force us to believe about the nature of the world? I would ask, What is the most. simple and general picture of the world that we can formulate that is not ruled by these experiments? I realized that medical and biological investigators were not attacking their problems the same way that theoretical physicists do, the way I had been in the habit of doing.

Einstein’s 1905 paper came out and suddenly changed people’s thinking about space-time. We’re again [2007] in the middle of something like that. When the dust settles, time—whatever it may be—could turn out to be even stranger and more illusory than even Einstein could imagine.

Enzymes are things invented by biologists that explain things which otherwise require harder thinking.

Essentially only one thing in life interests us: our psychical constitution, the mechanism of which was and is wrapped in darkness. All human resources, art, religion, literature, philosophy and historical sciences, all of them join in bringing lights in this darkness. But man has still another powerful resource: natural science with its strictly objective methods. This science, as we all know, is making huge progress every day. The facts and considerations which I have placed before you at the end of my lecture are one out of numerous attempts to employ a consistent, purely scientific method of thinking in the study of the mechanism of the highest manifestations of life in the dog, the representative of the animal kingdom that is man's best friend.

Every Man being conscious to himself, That he thinks, and that which his Mind is employ'd about whilst thinking, being the Ideas, that are there, 'tis past doubt, that Men have in their Minds several Ideas, such as are those expressed by the words, Whiteness, Hardness, Sweetness, Thinking, Motion, Man, Elephant, Army, Drunkenness, and others: It is in the first place then to be inquired, How he comes by them? I know it is a received Doctrine, That Men have native Ideas, and original Characters stamped upon their Minds, in their very first Being.

Every man has some forte something he can do better than he can do anything else. Many men, however, never find the job they are best fitted for. And often this is because they do not think enough. Too many men drift lazily into any job, suited or unsuited for them; and when they don’t get along well they blame everybody and everything except themselves.

Exercise in the most rigorous thinking that is possible will of its own accord strengthen the sense of truth and right, for each advance in the ability to distinguish between correct and false thoughts, each habit making for rigour in thought development will increase in the sound pupil the ability and the wish to ascertain what is right in life and to defend it.

Expertise in one field does not carry over into other fields. But experts often think so. The narrower their field of knowledge the more likely they are to think so.

Faraday thinks from day to day, against a background of older thinking, and anticipating new facts of tomorrow. In other words, he thinks in three dimensions of time; past, present, and future.

Fear of something is at the root of hate for others and hate within will eventually destroy the hater. Keep your thoughts free from hate, and you will have no fear from those who hate you. ...
David, though small, was filled with truth, right thinking and good will for others. Goliath represents one who let fear into his heart, and it stayed there long enough to grow into hate for others.

Few people think more than two or three times a year. I have made an international reputation for myself by thinking once or twice a week.

Fields of learning are surrounded ultimately only by illusory boundaries—like the “rooms” in a hall of mirrors.
It is when the illusion is penetrated that progress takes place. … Likewise science cannot be regarded as a thing apart, to be studied, admired or ignored. It is a vital part of our culture, our culture is part of it, it permeates our thinking, and its continued separateness from what is fondly called “the humanities” is a preposterous practical joke on all thinking men.

Finally, since I thought that we could have all the same thoughts, while asleep, as we have while we are awake, although none of them is true at that time, I decided to pretend that nothing that ever entered my mind was any more true than the illusions of my dreams. But I noticed, immediately afterwards, that while I thus wished to think that everything was false, it was necessarily the case that I, who was thinking this, was something. When I noticed that this truth “I think, therefore I am” was so firm and certain that all the most extravagant assumptions of the sceptics were unable to shake it, I judged that I could accept it without scruple as the first principle of the philosophy for which I was searching. Then, when I was examining what I was, I realized that I could pretend that I had no body, and that there was no world nor any place in which I was present, but I could not pretend in the same way that I did not exist. On the contrary, from the very fact that I was thinking of doubting the truth of other things, it followed very evidently and very certainly that I existed; whereas if I merely ceased to think, even if all the rest of what I had ever imagined were true, I would have no reason to believe that I existed. I knew from this that I was a substance, the whole essence or nature of which was to think and which, in order to exist, has no need of any place and does not depend on anything material. Thus this self—that is, the soul by which I am what I am—is completely distinct from the body and is even easier to know than it, and even if the body did not exist the soul would still be everything that it is.

First, as concerns the success of teaching mathematics. No instruction in the high schools is as difficult as that of mathematics, since the large majority of students are at first decidedly disinclined to be harnessed into the rigid framework of logical conclusions. The interest of young people is won much more easily, if sense-objects are made the starting point and the transition to abstract formulation is brought about gradually. For this reason it is psychologically quite correct to follow this course.
Not less to be recommended is this course if we inquire into the essential purpose of mathematical instruction. Formerly it was too exclusively held that this purpose is to sharpen the understanding. Surely another important end is to implant in the student the conviction that correct thinking based on true premises secures mastery over the outer world. To accomplish this the outer world must receive its share of attention from the very beginning.
Doubtless this is true but there is a danger which needs pointing out. It is as in the case of language teaching where the modern tendency is to secure in addition to grammar also an understanding of the authors. The danger lies in grammar being completely set aside leaving the subject without its indispensable solid basis. Just so in Teaching of Mathematics it is possible to accumulate interesting applications to such an extent as to stunt the essential logical development. This should in no wise be permitted, for thus the kernel of the whole matter is lost. Therefore: We do want throughout a quickening of mathematical instruction by the introduction of applications, but we do not want that the pendulum, which in former decades may have inclined too much toward the abstract side, should now swing to the other extreme; we would rather pursue the proper middle course.

For God's sake, stop researching for a while and begin to think.

For many of us, water simply flows from a faucet, and we think little about it beyond this point of contact. We have lost a sense of respect for the wild river, for the complex workings of a wetland, for the intricate web of life that water supports.

For me the most beautiful thing about Meccano is that it teaches you to think.

For me too, the periodic table was a passion. ... As a boy, I stood in front of the display for hours, thinking how wonderful it was that each of those metal foils and jars of gas had its own distinct personality.
[Referring to the periodic table display in the Science Museum, London, with element samples in bottles]

For myself, I like a universe that, includes much that is unknown and, at the same time, much that is knowable. A universe in which everything is known would be static and dull, as boring as the heaven of some weak-minded theologians. A universe that is unknowable is no fit place for a thinking being. The ideal universe for us is one very much like the universe we inhabit. And I would guess that this is not really much of a coincidence.

Furious activity is no substitute for analytical thought.

Good work is no done by “humble” men. It is one of the first duties of a professor, for example, in any subject, to exaggerate a little both the importance of his subject and his own importance in it. A man who is always asking “Is what I do worth while?” and “Am I the right person to do it?” will always be ineffective himself and a discouragement to others. He must shut his eyes a little and think a little more of his subject and himself than they deserve. This is not too difficult: it is harder not to make his subject and himself ridiculous by shutting his eyes too tightly.

Great minds don't think alike. If they did, the Patent Office would only have about fifty inventions.

He had constructed for himself a certain system which thereafter exercised such an influence on his way of thinking that those who observed him always saw his judgment walking a few steps in front of his feeling, though he himself believed it was keeping to the rear.

How can a modern anthropologist embark upon a generalization with any hope of arriving at a satisfactory conclusion? By thinking of the organizational ideas that are present in any society as a mathematical pattern.

How many famous men be there in this our age, which make scruple to condemne these old witches, thinking it to bee nothing but a melancholike humour which corrupteth thei imagination, and filleth them with all these vaines toyes. I will not cast my selfe any further into the depth of this question, the matter craveth a man of more leisure.
Describing melancholy as the innocent affliction of those regarded as witches instead of Satanic influence, while distancing himself from the controversy.

How much has happened in these fifty years—a period more remarkable than any, I will venture to say, in the annals of mankind. I am not thinking of the rise and fall of Empires, the change of dynasties, the establishment of Governments. I am thinking of those revolutions of science which have had much more effect than any political causes, which have changed the position and prospects of mankind more than all the conquests and all the codes and all the legislators that ever lived.

How near one Species to the next is join'd,
The due Gradations please a thinking Mind;
and there are Creatures which no eye can see,
That for a Moment live and breathe like me:
Whom a small Fly in bulk as far exceeds,
As yon tall Cedar does the waving Reeds:
These we can reach—and may we not suppose
There still are Creatures more minute than those.

However, all scientific statements and laws have one characteristic in common: they are “true or false” (adequate or inadequate). Roughly speaking, our reaction to them is “yes” or “no.” The scientific way of thinking has a further characteristic. The concepts which it uses to build up its coherent systems are not expressing emotions. For the scientist, there is only “being,” but no wishing, no valuing, no good, no evil; no goal. As long as we remain within the realm of science proper, we can never meet with a sentence of the type: “Thou shalt not lie.” There is something like a Puritan's restraint in the scientist who seeks truth: he keeps away from everything voluntaristic or emotional.

Humans are not by nature the fact-driven, rational beings we like to think we are. We get the facts wrong more often than we think we do. And we do so in predictable ways: we engage in wishful thinking. We embrace information that supports our beliefs and reject evidence that challenges them. Our minds tend to take shortcuts, which require some effort to avoid … [and] more often than most of us would imagine, the human mind operates in ways that defy logic.

I am a believer in unconscious cerebration. The brain is working all the time, though we do not know it. At night it follows up what we think in the daytime. When I have worked a long time on one thing, I make it a point to bring all the facts regarding it together before I retire; I have often been surprised at the results… We are thinking all the time; it is impossible not to think.

I am always surprised when a young man tells me he wants to work at cosmology. I think of cosmology as something that happens to one, not something one can choose.

I am merely thinking God’s thoughts after him.

I am one of those who think, like Nobel, that humanity will draw more good than evil from new discoveries.

I am the thought you are now thinking.

I beseech you in the bowels of Christ, think it possible you may be mistaken.

I cannot think of a single field in biology or medicine in which we can claim genuine understanding, and it seems to me the more we learn about living creatures, especially ourselves, the stranger life becomes.

I carried this problem around in my head basically the whole time. I would wake up with it first thing in the morning, I would be thinking about it all day, and I would be thinking about it when I went to sleep. Without distraction I would have the same thing going round and round in my mind.
Recalling the degree of focus and determination that eventually yielded the proof of Fermat's Last Theorem.

I do not know whether my distrust of men of science is congenital or acquired, but I think I should have transmitted it to descendants.

I do not think that G. H. Hardy was talking nonsense when he insisted that the mathematician was discovering rather than creating, nor was it wholly nonsense for Kepler to exult that he was thinking God's thoughts after him. The world for me is a necessary system, and in the degree to which the thinker can surrender his thought to that system and follow it, he is in a sense participating in that which is timeless or eternal.

I do not think words alone will solve humanity’s present problems. The sound of bombs drowns out men’s voices. In times of peace I have great faith in the communication of ideas among thinking men, but today, with brute force dominating so many millions of lives, I fear that the appeal to man’s intellect is fast becoming virtually meaningless.

I had gone on a walk on a fine Sabbath afternoon. I had entered the Green [of Glasgow] by the gate at the foot of Charlotte Street—had passed the old washing-house. I was thinking upon the engine at the time, and had gone as far as the herd's house, when the idea came into my mind that as steam was an elastic body it would rush into a vacuum, and if a communication were made between the cylinder and an exhausted vessel it would rush into it, and might be there condensed without cooling the cylinder. I then saw that I must get rid of the condensed steam and injection water if I used a jet, as in Newcomen's engine. Two ways of doing this occurred to me. First, the water might be run off by a descending pipe, if an outlet could be got at the depth of 35 or 36 feet, and any air might be extracted by a small pump. The second was to make the pump large enough to extract both water and air. ... I had not walked further than the Golf-house when the whole thing was arranged in my mind.
[In Robert Hart's words, a recollection of the description of Watt's moment of inspiration, in May 1765, for improving Thomas Newcomen's steam engine.]

I had no books as a child. I had real machines, and I went out to work in the fields. I was driving farm machinery at five, and fixing it at age seven or eight. It’s no accident that I worked on Hubble 50 to 60 years later. My books were nature; it was very important to how I related to the Earth, and the Earth from space. No doubt when I go into space, I go back into the cool soil of Earth. I’m always thinking of it. Nature was my book. Other people come from that tradition - Emerson, Thoreau, and especially Whitman. Look at what they said in their philosophy - go out and have a direct relationship with nature.
When asked by Discover magazine what books helped inspire his passion as an astronaut.

I have never had any student or pupil under me to aid me with assistance; but have always prepared and made my experiments with my own hands, working & thinking at the same time. I do not think I could work in company, or think aloud, or explain my thoughts at the time. Sometimes I and my assistant have been in the Laboratory for hours & days together, he preparing some lecture apparatus or cleaning up, & scarcely a word has passed between us; — all this being a consequence of the solitary & isolated system of investigation; in contradistinction to that pursued by a Professor with his aids & pupils as in your Universities.

I have never thought that you could obtain the extremely clumpy, heterogeneous universe we have today, strongly affected by plasma processes, from the smooth, homogeneous one of the Big Bang, dominated by gravitation.

I have tried to read philosophers of all ages and have found many illuminating ideas but no steady progress toward deeper knowledge and understanding. Science, however, gives me the feeling of steady progress: I am convinced that theoretical physics is actual philosophy. It has revolutionized fundamental concepts, e.g., about space and time (relativity), about causality (quantum theory), and about substance and matter (atomistics), and it has taught us new methods of thinking (complementarity) which are applicable far beyond physics.

I have written many direct and indirect arguments for the Copernican view, but until now I have not dared to publish them, alarmed by the fate of Copernicus himself, our master. He has won for himself undying fame in the eyes of a few, but he has been mocked and hooted at by an infinite multitude (for so large is the number of fools). I would dare to come forward publicly with my ideas if there were more people of your [Johannes Kepler’s] way of thinking. As this is not the case, I shall refrain.

I kind of like scientists, in a funny way. … I'm kind of interested in genetics though. I think I would have liked to have met Gregor Mendel. Because he was a monk who just sort of figured this stuff out on his own. That's a higher mind, that’s a mind that's connected. … But I would like to know about Mendel, because I remember going to the Philippines and thinking “this is like Mendel’s garden” because it had been invaded by so many different countries over the years, and you could see the children shared the genetic traits of all their invaders over the years, and it made for this beautiful varietal garden.

I learned a lot of different things from different schools. MIT is a very good place…. It has developed for itself a spirit, so that every member of the whole place thinks that it’s the most wonderful place in the world—it’s the center, somehow, of scientific and technological development in the United States, if not the world … and while you don’t get a good sense of proportion there, you do get an excellent sense of being with it and in it, and having motivation and desire to keep on…

I never pick up an item without thinking of how I might improve it. I never perfected an invention that I did not think about in terms of the service it might give others. I want to save and advance human life, not destroy it. I am proud of the fact that I never invented weapons to kill. The dove is my emblem.

I never said a word against eminent men of science. What I complain of is a vague popular philosophy which supposes itself to be scientific when it is really nothing but a sort of new religion and an uncommonly nasty one. When people talked about the fall of man, they knew they were talking about a mystery, a thing they didn’t understand. Now they talk about the survival of the fittest: they think they do understand it, whereas they have not merely no notion, they have an elaborately false notion of what the words mean.

I propose to consider the question, ‘Can machines think?’

I refrained from writing another one, thinking to myself: Never mind, I will prove that I am able to become a greater scientist than some of you, even without the title of doctor.

I remember growing up thinking that astronauts and their job was the coolest thing you could possibly do... But I absolutely couldn’t identify with the people who were astronauts. I thought they were movie stars.

I sometimes think about the tower at Pisa as the first particle accelerator, a (nearly) vertical linear accelerator that Galileo used in his studies.

I spend a great deal of the hours that I’m awake within myself. You never want to stop doing it, especially when it’s a pleasure. It’s vital to my existence and I couldn’t live if I wasn’t an inventor.

I suddenly realized that no one knew anything. … From that moment I began to think for myself or rather knew that I could.