“What place would you advise me to visit now?” he asked. “The planet Earth,” replied the geographer. “It has a good reputation.”

[Certain students] suppose that because science has penetrated the structure of the atom it can solve all the problems of the universe. ... They are known in every ... college as the most insufferable, cocksure know-it-alls. If you want to talk to them about poetry, they are likely to reply that the "emotive response" to poetry is only a conditioned reflex .... If they go on to be professional scientists, their sharp corners are rubbed down, but they undergo no fundamental change. They most decidedly are not set apart from the others by their intellectual integrity and faith, and their patient humility in front of the facts of nature.... They are uneducated, in the fullest sense of the word, and they certainly are no advertisement for the claims of science teachers.

[I have] a strong conviction that controversial reply and rejoinder is but a vain occupation.

[N]o scientist likes to be criticized. … But you don’t reply to critics: “Wait a minute, wait a minute; this is a really good idea. I’m very fond of it. It’s done you no harm. Please don’t attack it.” That's not the way it goes. The hard but just rule is that if the ideas don't work, you must throw them away. Don't waste any neurons on what doesn’t work. Devote those neurons to new ideas that better explain the data. Valid criticism is doing you a favor.

[Reply to a lady enquiring: “Have we lost faith?”] Certainly not, but we have only transferred it from God to the General Medical Council.

[Reply when questioned, “Don’t you find it very inconvenient stammering, Dr. Darwin?”] No, sir, because I have time to think before I speak, and don’t ask impertinent questions.

[In reply to a question about how he got his expertise:]
By studying the masters and not their pupils.

Are coral reefs growing from the depths of the oceans? ... [The] reply is a simple negative; and a single fact establishes its truth. The reef-forming coral zoophytes, as has been shown, cannot grow at greater depths than 100 or 120 feet; and therefore in seas deeper than this, the formation or growth of reefs over the bottom is impossible.

Meine Herren, der Senat ist doch keine Badeanstalt.
The faculty is not a pool changing room.
Indignant reply to the blatent sex discrimination expressed in a colleague’s opposition when Hilbert proposed appointing Emmy Noether as the first woman professor at their university.

Reply when questioned on the safety of the polio vaccine he developed: It is safe, and you can’t get safer than safe.

A line is not made up of points. … In the same way, time is not made up of parts considered as indivisible “nows.”
Part of Aristotle’s reply to Zeno's paradox concerning continuity.

A man said to the universe,
“Sir, I exist.”
“However,” replied the universe,
“the fact has not created in me
a sense of obligation.”

A Native American elder once described his own inner struggles in this manner: Inside of me there are two dogs. One of the dogs is mean and evil. The other dog is good. The mean dog fights the good dog all the time. When asked which dog wins, he reflected for a moment and replied, The one I feed the most.

After having a wash I proceeded to the bar where—believe it or not—there was a white-coated barman who was not only serving drinks but also cigarettes! I hastened forward and rather timidly said ‘Can I have some cigarettes?’
‘What’s your rank?’ was the slightly unexpected reply.
‘I am afraid I haven’t got one,’ I answered.
‘Nonsense—everyone who comes here has a rank.’
‘I’m sorry but I just don’t have one.’
‘Now that puts me in a spot,’ said the barman, ‘for orders about cigarettes in this camp are clear—twenty for officers and ten for other ranks. Tell me what exactly are you?’
Now I really wanted those cigarettes so I drew myself up and said ‘I am the Professor of Chemistry at Manchester University.’
The barman contemplated me for about thirty seconds and then said ‘I’ll give you five.’
Since that day I have had few illusions about the importance of professors!

An enthusiastic philosopher, of whose name we are not informed, had constructed a very satisfactory theory on some subject or other, and was not a little proud of it. “But the facts, my dear fellow,” said his friend, “the facts do not agree with your theory.”—“Don't they?” replied the philosopher, shrugging his shoulders, “then, tant pis pour les faits;”—so much the worse for the facts!

An incidental remark from a German colleague illustrates the difference between Prussian ways and our own. He had apparently been studying the progress of our various crews on the river, and had been struck with the fact that though the masters in charge of the boats seemed to say and do very little, yet the boats went continually faster and faster, and when I mentioned Dr. Young’s book to him, he made the unexpected but suggestive reply: “Mathematics in Prussia! Ah, sir, they teach mathematics in Prussia as you teach your boys rowing in England: they are trained by men who have been trained by men who have themselves been trained for generations back.”

An insolent reply from a polite person is a bad sign.

And so many think incorrectly that everything was created by the Creator in the beginning as it is seen, that not only the mountains, valleys, and waters, but also various types of minerals occurred together with the rest of the world, and therefore it is said that it is unnecessary to investigate the reasons why they differ in their internal properties and their locations. Such considerations are very dangerous for the growth of all the sciences, and hence for natural knowledge of the Earth, particularly the art of mining, though it is very easy for those clever people to be philosophers, having learnt by heart the three words 'God so created' and to give them in reply in place of all reasons.

Are the atoms of the dextroacid (tartaric) grouped in the spirals of a right-hand helix or situated at the angles of an irregular tetrahedron, or arranged in such or such particular unsymmetrical fashion? We are unable to reply to these questions. But there can be no reason for doubting that the grouping of the atoms has an unsymmetrical arrangement with a non-superimposable image. It is not less certain that the atoms of the laevo-acid realize precisely an unsymmetrical arrangement of the inverse of the above.

August 29, 1662. The council and fellows of the Royal Society went in a body to Whitehall to acknowledge his Majesty’s royal grace to granting our charter and vouchsafing to be himself our founder; then the president gave an eloquent speech, to which his Majesty gave a gracious reply and we all kissed his hand. Next day, we went in like manner with our address to my Lord Chancellor, who had much prompted our patent.

Dr. Paget was conducting a school examination, and in the course of his questions he happened to ask a small child the meaning of “Average.” He was utterly bewildered by the reply, “The thing that hens lay on,” until the child explained that he had read in a book that hens lay on an average so many eggs a year.

I am just laboring in the vineyard. I am at the operating table, and I make my rounds. I believe there is a cross-fertilization between writing and surgery. If I withdraw from surgery, I would not have another word to write. Having become a writer makes me a better doctor.
[Reply to reporter's question whether he would rather be a full-time writer instead of a surgeon.]

I cannot afford to waste my time making money.
A reply to an offer of a lecture tour.

I confess that Fermat’s Theorem as an isolated proposition has very little interest for me, for a multitude of such theorems can easily be set up, which one could neither prove nor disprove. But I have been stimulated by it to bring our again several old ideas for a great extension of the theory of numbers. Of course, this theory belongs to the things where one cannot predict to what extent one will succeed in reaching obscurely hovering distant goals. A happy star must also rule, and my situation and so manifold distracting affairs of course do not permit me to pursue such meditations as in the happy years 1796-1798 when I created the principal topics of my Disquisitiones arithmeticae. But I am convinced that if good fortune should do more than I expect, and make me successful in some advances in that theory, even the Fermat theorem will appear in it only as one of the least interesting corollaries.
In reply to Olbers' attempt in 1816 to entice him to work on Fermat's Theorem. The hope Gauss expressed for his success was never realised.

I often get letters … from people who say … I never give credit to the almighty power that created nature. … I reply … “Well, it’s funny that the people, when they say that this is evidence of the Almighty, always quote beautiful things … orchids and hummingbirds and butterflies and roses.” But I always have to think too of a little boy sitting on the banks of a river in west Africa who has a worm boring through his eyeball, turning him blind before he’s five years old. And I … say, “Well, presumably the God you speak about created the worm as well,” and now, I find that baffling to credit a merciful God with that action. And therefore it seems to me safer to show things that I know to be truth, truthful and factual, and allow people to make up their own minds about the moralities of this thing, or indeed the theology of this thing.

I specifically paused to show that, if there were such machines with the organs and shape of a monkey or of some other non-rational animal, we would have no way of discovering that they are not the same as these animals. But if there were machines that resembled our bodies and if they imitated our actions as much as is morally possible, we would always have two very certain means for recognizing that, none the less, they are not genuinely human. The first is that they would never be able to use speech, or other signs composed by themselves, as we do to express our thoughts to others. For one could easily conceive of a machine that is made in such a way that it utters words, and even that it would utter some words in response to physical actions that cause a change in its organs—for example, if someone touched it in a particular place, it would ask what one wishes to say to it, or if it were touched somewhere else, it would cry out that it was being hurt, and so on. But it could not arrange words in different ways to reply to the meaning of everything that is said in its presence, as even the most unintelligent human beings can do. The second means is that, even if they did many things as well as or, possibly, better than anyone of us, they would infallibly fail in others. Thus one would discover that they did not act on the basis of knowledge, but merely as a result of the disposition of their organs. For whereas reason is a universal instrument that can be used in all kinds of situations, these organs need a specific disposition for every particular action.

If a superior alien civilisation sent us a message saying, “We’ll arrive in a few decades,” would we just reply, “OK, call us when you get here—we’ll leave the lights on”? Probably not—but this is more or less what is happening with AI. Although we are facing potentially the best or worst thing to happen to humanity in history, little serious research is devoted to these issues outside non-profit institutes such as the Cambridge Centre for the Study of Existential Risk, the Future of Humanity Institute, the Machine Intelligence Research Institute, and the Future of Life Institute. All of us should ask ourselves what we can do now to improve the chances of reaping the benefits and avoiding the risks.

If to-day you ask a physicist what he has finally made out the æther or the electron to be, the answer will not be a description in terms of billiard balls or fly-wheels or anything concrete; he will point instead to a number of symbols and a set of mathematical equations which they satisfy. What do the symbols stand for? The mysterious reply is given that physics is indifferent to that; it has no means of probing beneath the symbolism. To understand the phenomena of the physical world it is necessary to know the equations which the symbols obey but not the nature of that which is being symbolised. …this newer outlook has modified the challenge from the material to the spiritual world.

In answer to the question, “Was the development of the atomic bomb by the United States necessary?” I reply unequivocally, “Yes.” To the question, “Is atomic energy a force for good or for evil?” I can only say, “As mankind wills it.”

In the 1860s, Pasteur not only applied his germ theory to create “Pasteurization,” rescuing France’s wine and vinegar industries, but also found both the cause and cure of silkworm disease, saving growers millions of dollars. When Napoleon asked the scientist why he had not legitimately profited by his findings, Pasteur replied: “In France scientists would consider they lowered themselves by doing so.”

It was an admirable reply of a converted astronomer, who, when interrogated concerning his comparative estimate of religion and the science he had formerly idolized, answered, 'I am now bound for heaven, and I take the stars in my way.'

John Bahcall, an astronomer on the Institute of Advanced Study faculty since 1970 likes to tell the story of his first faculty dinner, when he found himself seated across from Kurt Gödel, … a man dedicated to logic and the clean certainties of mathematical abstraction. Bahcall introduced himself and mentioned that he was a physicist. Gödel replied, “I don’t believe in natural science.”

Many Species of Animals have been lost out of the World, which Philosophers and Divines are unwilling to admit, esteeming the Destruction of anyone Species a Dismembring of the Universe, and rendring the World imperfect; whereas they think the Divine Providence is especially concerned, and solicitous to secure and preserve the Works of the Creation. And truly so it is, as appears, in that it was so careful to lodge all Land Animals in the Ark at the Time of the general Deluge; and in that, of all Animals recorded in Natural Histories, we cannot say that there hath been anyone Species lost, no not of the most infirm, and most exposed to Injury and Ravine. Moreover, it is likely, that as there neither is nor can be any new Species of Animals produced, all proceeding from Seeds at first created; so Providence, without which one individual Sparrow falls not to the ground, doth in that manner watch over all that are created, that an entire Species shall not be lost or destroyed by any Accident. Now, I say, if these Bodies were sometimes the Shells and Bones of Fish, it will thence follow, that many Species have been lost out of the World... To which I have nothing to reply, but that there may be some of them remaining some where or other in the Seas, though as yet they have not come to my Knowledge. Far though they may have perished, or by some Accident been destroyed out of our Seas, yet the Race of them may be preserved and continued still in others.

Nonmathematical people sometimes ask me, “You know math, huh? Tell me something I’ve always wondered, What is infinity divided by infinity?” I can only reply, “The words you just uttered do not make sense. That was not a mathematical sentence. You spoke of ‘infinity’ as if it were a number. It’s not. You may as well ask, 'What is truth divided by beauty?’ I have no clue. I only know how to divide numbers. ‘Infinity,’ ‘truth,’ ‘beauty’—those are not numbers.”

On one occasion when [William] Smart found him engrossed with his fundamental theory, he asked Eddington how many people he thought would understand what he was writing—after a pause came the reply, 'Perhaps seven.'

On Sept 15th [1852] Mr Goulburn, Chancellor of the Exchequer, asked my opinion on the utility of Mr Babbage's calculating machine, and the propriety of spending further sums of money on it. I replied, entering fully into the matter, and giving my opinion that it was worthless.

One morning a great noise proceeded from one of the classrooms [of the Braunsberger gymnasium] and on investigation it was found that Weierstrass, who was to give the recitation, had not appeared. The director went in person to Weierstrass’ dwelling and on knocking was told to come in. There sat Weierstrass by a glimmering lamp in a darkened room though it was daylight outside. He had worked the night through and had not noticed the approach of daylight. When the director reminded him of the noisy throng of students who were waiting for him, his only reply was that he could impossibly interrupt his work; that he was about to make an important discovery which would attract attention in scientific circles.

One of the earliest questions asked by an intelligent child is: “What is this made of?” “What is that made of?” And the answer is generally more or less satisfactory. For example, if the question relates to butter, the reply may be, “From cream.” It may be explained, besides, that when cream is beaten up, or churned, the butter separates, leaving skim-milk behind. But the question has not been answered. The child may ask, “Was the butter in the milk before it was churned? or has it been made out of the milk by the churning?” Possibly the person to whom the question is addressed may know that the milk contained the butter in the state of fine globules, and that the process of churning breaks up the globules, and causes them to stick together. The original question has not really been answered; and indeed it is not an easy one to reply to. Precisely such questions suggested themselves to the people of old, and they led to many speculations.

Our national policies will not be revoked or modified, even for scientists. If the dismissal of Jewish scientists means the annihilation of contemporary German science, then we shall do without science for a few years.
Reply to Max Planck (President of the Kaiser Wilhelm Society for the Advancement of Science) when he tried to petition the Fuhrer to stop the dismissal of scientists on political grounds.

Professor Ayrton said that we were gradually coming within thinkable distance of the realization of a prophecy he had ventured to make four years before, of a time when, if a person wanted to call to a friend he knew not where, he would call in a very loud electromagnetic voice, heard by him who had the electromagnetic ear, silent to him who had it not. “Where are you?” he would say. A small reply would come, “I am at the bottom of a coalmine, or crossing the Andes, or in the middle of the Atlantic.” Or, perhaps in spite of all the calling, no reply would come, and the person would then know that his friend was dead. Think of what this would mean ... a real communication from a distance based on true physical laws.
[His prophecy of cell phones, as a comment on Marconi's paper, 'Syntonic Wireless Telegraphy,' read before the Society of Arts, 15 May 1901, about his early radio signal experiments.]

Reason must approach nature with the view, indeed, of receiving information from it, not, however, in the character of a pupil, who listens to all that his master chooses to tell him, but in that of a judge, who compels the witnesses to reply to those questions which he himself thinks fit to propose. To this single idea must the revolution be ascribed, by which, after groping in the dark for so many centuries, natural science was at length conducted into the path of certain progress.

Some of my cousins who had the great advantage of University education used to tease me with arguments to prove that nothing has any existence except what we think of it. … These amusing mental acrobatics are all right to play with. They are perfectly harmless and perfectly useless. ... I always rested on the following argument. … We look up to the sky and see the sun. Our eyes are dazzled and our senses record the fact. So here is this great sun standing apparently on no better foundation than our physical senses. But happily there is a method, apart altogether from our physical senses, of testing the reality of the sun. It is by mathematics. By means of prolonged processes of mathematics, entirely separate from the senses, astronomers are able to calculate when an eclipse will occur. They predict by pure reason that a black spot will pass across the sun on a certain day. You go and look, and your sense of sight immediately tells you that their calculations are vindicated. So here you have the evidence of the senses reinforced by the entirely separate evidence of a vast independent process of mathematical reasoning. We have taken what is called in military map-making “a cross bearing.” When my metaphysical friends tell me that the data on which the astronomers made their calculations, were necessarily obtained originally through the evidence of the senses, I say, “no.” They might, in theory at any rate, be obtained by automatic calculating-machines set in motion by the light falling upon them without admixture of the human senses at any stage. When it is persisted that we should have to be told about the calculations and use our ears for that purpose, I reply that the mathematical process has a reality and virtue in itself, and that onie discovered it constitutes a new and independent factor. I am also at this point accustomed to reaffirm with emphasis my conviction that the sun is real, and also that it is hot— in fact hot as Hell, and that if the metaphysicians doubt it they should go there and see.

Tait once urged the advantage of Quaternions on Cayley (who never used them), saying: “You know Quaternions are just like a pocket-map.” “That may be,” replied Cayley, “but you’ve got to take it out of your pocket, and unfold it, before it’s of any use.” And he dismissed the subject with a smile.

The average gambler will say “The player who stakes his whole fortune on a single play is a fool, and the science of mathematics can not prove him to be otherwise.” The reply is obvious: “The science of mathematics never attempts the impossible, it merely shows that other players are greater fools.”

The canyon country does not always inspire love. To many it appears barren, hostile, repellent—a fearsome, mostly waterless land of rock and heat, sand dunes and quicksand. cactus, thornbush, scorpion, rattlesnake, and agoraphobic distances. To those who see our land in that manner, the best reply is, yes, you are right, it is a dangerous and terrible place. Enter at your own risk. Carry water. Avoid the noon-day sun. Try to ignore the vultures. Pray frequently.

The general acceptance of the validity of science is a very recent phenomenon. As late as 1880, Huxley complained that “no reply to a troublesome argument tells so well as calling its author a ‘mere scientific specialist.’”

The greatest of all spectral classifiers, Antonia Maury had two strikes on her: the biggest one was, she was a woman. A woman had no chance at anything in astronomy except at Harvard in the 1880’s and 1890’s. And even there, things were rough. It now turns out that her director, E.C. Pickering, did not like the way she classified; she then refused to change to suit him; and after her great publication in Harvard Annals 28 (1897), she left Harvard—and in a sense, astronomy. ... I would say the most remarkable phenomenological investigation in modern astronomy is Miss Maury’s work in Harvard Annals 28. She didn’t have anything astrophysical to go on. Investigations between 1890 and 1900 were the origin of astrophysics. But these were solar, mostly. And there Miss Maury was on the periphery. I’ve seen pictures of groups, where she’d be standing away a little bit to one side of the other people, a little bit in the background. It was a very sad thing. When Hertzsprung wrote Pickering to congratulate him on Miss Maury’s work that had led to Hertzsprung’s discovery of super giants, Pickering is supposed to have replied that Miss Maury’s work was wrong — could not possibly be correct.

The republic has no need of scientists [savants].
Apocryphal remark; supposedly the judge’s reply to Lavoisier when he appealed at his trial for more time to complete his scientific work.

The task of asking nonliving matter to speak and the responsibility for interpreting its reply is that of physics.

There is a story which shows his ready wit, dating from the meeting of the British Association in Canada before the war. Tizard and a colleague inadvertently crossed over into the United States, near Niagara. When challenged by a policeman, and not having their passports with them, they produced their British Association membership cards. When the policeman told them that “The American Government doesn't recognise British Science,” the lightning reply came from Tizard, “Oh, that's all right, neither does the British Government.”

There is, I conceive, no contradiction in believing that mind is at once the cause of matter and of the development of individualised human minds through the agency of matter. And when, further on, [Mr Frederick F. Cook] asks, ‘Does mortality give consciousness to spirit, or does spirit give consciousness for a limited period to mortality?’ I would reply, ‘Neither the one nor the other; but, mortality is the means by which a permanent individuality is given to spirit.’

They say that Ptolemy once asked him [Euclid] whether there was in geometry no shorter way than that of the elements and he replied, “There is no royal road to geometry”.

This marvellous experimental method eliminates certain facts, brings forth others, interrogates nature, compels it to reply and stops only when the mind is fully satisfied. The charm of our studies, the enchantment of science, is that, everywhere and always, we can give the justification of our principles and the proof of our discoveries.

To most people, I fancy, the stars are beautiful; but if you asked why, they would be at a loss to reply, until they remembered what they had heard about astronomy, and the great size and distance and possible habitation of those orbs. ... [We] persuade ourselves that the power of the starry heavens lies in the suggestion of astronomical facts.

Were I asked to define it, I should reply that archæology is that science which enables us to register and classify our knowledge of the sum of man’s achievement in those arts and handicrafts whereby he has, in time past, signalized his passage from barbarism to civilization.

What strange wonder is this? Our prayer to thee was for water,
Earth! What is this that thou now send’st from thy womb in reply?
In the abyss is there life ? Or hidden under the lava
Dwelleth some race now unknown? Does what hath fled e’er return?
Greeks and Romans, oh come! Oh, see the ancient Pompeii
Here is discover’d again,—Hercules’ town is rebuilt!

When two minds of a high order, interested in kindred subjects, come together, their conversation is chiefly remarkable for the summariness of its allusions and the rapidity of its transitions. Before one of them is half through a sentence the other knows his meaning and replies. ... His mental lungs breathe more deeply, in an atmosphere more broad and vast...

You don’t know who he was? Half the particles in the universe obey him!
[Reply by a physics professor when a student asked who Bose was.]