Le mur murant Paris rend Paris murmurant.
The wall surrounding Paris is making Paris grumble.
Parisian saying after the Farmers-General of taxes, acting on a proposal by Lavoisier, erected a customs wall around Paris.

Empty wagons make the most noise.

God gives every bird his food, but does not throw it into the nest.

He who lacks a sense of the past is condemned to live in the narrow darkness of his own generation

Post coitum omne animal triste.
After coition every animal is sad.

Post hoc, ergo propter hoc.
After this, therefore because of this.

Experiment adds to knowledge, Credulity leads to error.

Fiction tends to become “fact” simply by serial passage via the printed page.

Garbage in, garbage out.

Half of the secret of resistance to disease is cleanliness; the other half is dirtiness.

Here are the opinions on which my facts are based.

Gnothi seauton.
Know thyself.

Laws of Thermodynamics
1) You cannot win, you can only break even.
2) You can only break even at absolute zero.
3) You cannot reach absolute zero.

Like the statistician who was drowned in a lake of average depth six inches.

Man occasionally stumbles on the truth, but then just picks himself up and hurries on regardless.

The most powerful antigen in human biology is a new idea.

Nature is by nature perverse.

A physicist learns more and more about less and less, until he knows everything about nothing; whereas a philosopher learns less and less about more and more, until he knows nothing about everything.

Nihil est in intellectu quod non prius fuerit in sensu.
There is nothing in the mind that has not previously been in the senses.

There is one thing stronger than all the armies in the world; and that is an idea whose time has come.

Hie locus est ubi mars gaudet succurere vitae.
This place is where death rejoices to come to the aid of life.

Magna opera Domini exquisita in omnes voluntates eius.
The works of the Lord are great; sought out of all those that have pleasure therein.

Give me a place to stand, and I will move the earth.

Experience is a comb that Nature gives man after he has gone bald.

Everybody loves a fat man.

It will never get well if you pick it.

Nobody loves a fat man.

Dauer in Wechsel.
Duration in change.

God created, Linnaeus ordered.

Temporis fila.
Child of time.
A favourite expression of Linnaeus.

The saying that a little knowledge is a dangerous thing is, to my mind, a very dangerous adage. If knowledge is real and genuine, I do not believe that it is other than a very valuable posession, however infinitesimal its quantity may be. Indeed, if a little knowledge is dangerous, where is a man who has so much as to be out of danger?

I think modern science should graft functional wings on a pig, simply so no one can ever use that stupid saying again.

It is open to every man to choose the direction of his striving; and also every man may draw comfort from Lessing's fine saying, that the search for truth is more precious than its possession.

Frustra fit per plura, quod fieri potest per pauciora.
It is vain to do with more what can be done with less.

The doctrine of Darwinism had been tritely summed up in the saying, “from mud to monkey, from monkey up to man.”

Superficially, it might be said that the function of the kidneys is to make urine; but in a more considered view one can say that the kidneys make the stuff of philosophy itself.

There are those who say that the human kidney was created to keep the blood pure, or more precisely, to keep our internal environment in an ideal balanced state. This I must deny. I grant that the human kidney is a marvelous organ, but I cannot grant that it was purposefully designed to excrete urine or to regulate the composition of the blood or to subserve the physiological welfare of Homo sapiens in any sense. Rather I contend that the human kidney manufactures the kind of urine that it does, and it maintains the blood in the composition which that fluid has, because this kidney has a certain functional architecture; and it owes that architecture not to design or foresight or to any plan, but to the fact that the earth is an unstable sphere with a fragile crust, to the geologic revolutions that for six hundred million years have raised and lowered continents and seas, to the predacious enemies, and heat and cold, and storms and droughts; to the unending succession of vicissitudes that have driven the mutant vertebrates from sea into fresh water, into desiccated swamps, out upon the dry land, from one habitation to another, perpetually in search of the free and independent life, perpetually failing, for one reason or another, to find it.

Ostwald was a great protagonist and an inspiring teacher. He had the gift of saying the right thing in the right way. When we consider the development of chemistry as a whole, Ostwald's name like Abou ben Adhem's leads all the rest ... Ostwald was absolutely the right man in the right place. He was loved and followed by more people than any chemist of our time.

After that cancellation [of the Superconducting Super Collider in Texas, after $2 billion had been spent on it], we physicists learned that we have to sing for our supper. ... The Cold War is over. You can't simply say “Russia!” to Congress, and they whip out their checkbook and say, “How much?” We have to tell the people why this atom-smasher is going to benefit their lives.

Every sentence I utter must be understood not as an affirmation but as a question.
[A caution he gives his students, to be wary of dogmatism.]

“The Universe repeats itself, with the possible exception of history.” Of all earthly studies history is the only one that does not repeat itself. ... Astronomy repeats itself; botany repeats itself; trigonometry repeats itself; mechanics repeats itself; compound long division repeats itself. Every sum if worked out in the same way at any time will bring out the same answer. ... A great many moderns say that history is a science; if so it occupies a solitary and splendid elevation among the sciences; it is the only science the conclusions of which are always wrong.

This [the opening of the Vatican City radio station built by Marconi earlier in 1931] was a new demonstration of the harmony between science and religion that each fresh conquest of science ever more luminously confirms, so that one may say that those who speak of the incompatibility of science and religion either make science say that which it never said or make religion say that which it never taught.

I am entitled to say, if I like, that awareness exists in all the individual creatures on the planet—worms, sea urchins, gnats, whales, subhuman primates, superprimate humans, the lot. I can say this because we do not know what we are talking about: consciousness is so much a total mystery for our own species that we cannot begin to guess about its existence in others.

Many errors, of a truth, consist merely in the application of the wrong names of things. For if a man says that the lines which are drawn from the centre of the circle to the circumference are not equal, he understands by the circle, at all events for the time, something else than mathematicians understand by it.

Genetics as a whole is the great over-hyped science, and geneticists know that even if they don't say it. All that genetics really is is anatomy plus an enormous research group grant. It's what anatomists did in the fifteenth century-looking at the heart and seeing how it worked. Now, we are doing the same with DNA

Entropy theory is indeed a first attempt to deal with global form; but it has not been dealing with structure. All it says is that a large sum of elements may have properties not found in a smaller sample of them.

It may be said “In research, if you know what you are doing, then you shouldn't be doing it.” In a sense, if the answer turns out to be exactly what you expected, then you have learned nothing new, although you may have had your confidence increased somewhat.

It is very difficult to say nowadays where the suburbs of London come to an end and where the country begins. The railways, instead of enabling Londoners to live in the country have turned the countryside into a city.

I will venture to say there is more learning and science within the circumference of ten miles from where we now sit [in London], than in all the rest of the kingdom.

The traditional mathematics professor of the popular legend is absentminded. He usually appears in public with a lost umbrella in each hand. He prefers to face a blackboard and to turn his back on the class. He writes a, he says b, he means c, but it should be d. Some of his sayings are handed down from generation to generation:
“In order to solve this differential equation you look at it till a solution occurs to you.”
“This principle is so perfectly general that no particular application of it is possible.”
“Geometry is the science of correct reasoning on incorrect figures.”
“My method to overcome a difficulty is to go round it.”
“What is the difference between method and device? A method is a device which you used twice.”

Every great scientist becomes a great scientist because of the inner self-abnegation with which he stands before truth, saying: “Not my will, but thine, be done.” What, then, does a man mean by saying, Science displaces religion, when in this deep sense science itself springs from religion?

As the saying goes, the Stone Age did not end because we ran out of stones; we transitioned to better solutions. The same opportunity lies before us with energy efficiency and clean energy.

Notwithstanding all that has been discovered since Newton’s time, his saying that we are little children picking up pretty pebbles on the beach while the whole ocean lies before us unexplored remains substantially as true as ever, and will do so though we shovel up the pebbles by steam shovels and carry them off in carloads.

Humans are allergic to change. They love to say, “We’ve always done it this way.” I try to fight that. That’s why I have a clock on my wall that runs counter-clockwise.

A work of genius is something like the pie in the nursery song, in which the four and twenty blackbirds are baked. When the pie is opened, the birds begin to sing. Hereupon three fourths of the company run away in a fright; and then after a time, feeling ashamed, they would fain excuse themselves by declaring, the pie stank so, they could not sit near it. Those who stay behind, the men of taste and epicures, say one to another, We came here to eat. What business have birds, after they have been baked, to be alive and singing? This will never do. We must put a stop to so dangerous an innovation: for who will send a pie to an oven, if the birds come to life there? We must stand up to defend the rights of all the ovens in England. Let us have dead birds..dead birds for our money. So each sticks his fork into a bird, and hacks and mangles it a while, and then holds it up and cries, Who will dare assert that there is any music in this bird’s song?

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

In a scientific journal, a major consideration is whether the book reviewed has made a contribution to medical science. Cynics may well say that they know of no psychiatric text that would meet such conditions, and they may be right.

The psychiatric interviewer is supposed to be doing three things: considering what the patient could mean by what he says; considering how he himself can best phrase what he wishes to communicate to the patient; and, at the same time, observing the general pattern of the events being communicated. In addition to that, to make notes which will be of more than evocative value, or come anywhere near being a verbatim record of what is said, in my opinion is beyond the capacity of most human beings.

It is … a sign of the times—though our brothers of physics and chemistry may smile to hear me say so—that biology is now a science in which theories can be devised: theories which lead to predictions and predictions which sometimes turn out to be correct. These facts confirm me in a belief I hold most passionately—that biology is the heir of all the sciences.

In this country all a man need to do is to attain a little eminence and immediately he begins to talk. Usually his eminence is financial, and the greater this eminence the more he talks and the further his voice reaches. I don't blame the rich people for talking; many of them don’t know what else to do with themselves. The fault is with these who listen. If no one would listen no harm would he done. But the American people are willing to listen to any one who has attained prominence. The main fact is that we've heard a man's name a great many times; that makes us ready to accept whatever he says. … We listen to the one who talks the most and loudest.

We can’t define anything precisely. If we attempt to, we get into that paralysis of thought that comes to philosophers… one saying to the other: “You don’t know what you are talking about!” The second one says: “What do you mean by know? What do you mean by talking? What do you mean by you?”

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

It is like the man who became short-sighted and refused to wear glasses, saying there was nothing wrong with him, but that the trouble was that the recent papers were so badly printed.

The world is to me my proposition of it; and so is the pig’s world, the pig’s proposition of it; or, to use a common saying, “the pig sees with pig’s eyes.”

Mathematical economics is old enough to be respectable, but not all economists respect it. It has powerful supporters and impressive testimonials, yet many capable economists deny that mathematics, except as a shorthand or expository device, can be applied to economic reasoning. There have even been rumors that mathematics is used in economics (and in other social sciences) either for the deliberate purpose of mystification or to confer dignity upon commonplaces as French was once used in diplomatic communications. …. To be sure, mathematics can be extended to any branch of knowledge, including economics, provided the concepts are so clearly defined as to permit accurate symbolic representation. That is only another way of saying that in some branches of discourse it is desirable to know what you are talking about.

An old saying is “A penny for your thoughts.” The offer is not high enough: some thoughts would not be confessed for a million dollars.

It is said, sometimes, that common sense is very rare.