Again the message to experimentalists is: Be sensible but don't be impressed too much by negative arguments. If at all possible, try it and see what turns up. Theorists almost always dislike this sort of approach.

Alike fantastic, if too new, or old;
Be not the first by whom the new are try'd,
Not yet the last to lay the old aside.

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

I always keep two legs going, with one trying to reach ahead.

I always tried to live up to Leo Szilard's commandment, 'don't lie if you don't have to.' I had to. I filled up pages with words and plans I knew I would not follow. When I go home from my laboratory in the late afternoon, I often do not know what I am going to do the next day. I expect to think that up during the night. How could I tell them what I would do a year hence?

I happen to be a kind of monkey. I have a monkeylike curiosity that makes me want to feel, smell, and taste things which arouse my curiosity, then to take them apart. It was born in me. Not everybody is like that, but a scientific researchist should be. Any fool can show me an experiment is useless. I want a man who will try it and get something out of it.

If at first you don’t succeed, try, try, try again.

If that's how it all started, then we might as well face the fact that what's left out there is a great deal of shrapnel and a whole bunch of cinders (one of which is, fortunately, still hot enough and close enough to be good for tanning). Trying to find some sense and order in this mess may be as futile as trying to ... reconstruct the economy of Iowa from a bowl of popcorn.

If [science] tends to thicken the crust of ice on which, as it were, we are skating, it is all right. If it tries to find, or professes to have found, the solid ground at the bottom of the water it is all wrong. Our business is with the thickening of this crust by extending our knowledge downward from above, as ice gets thicker while the frost lasts; we should not try to freeze upwards from the bottom.

It is a happy world after all. The air, the earth, the water teem with delighted existence. In a spring noon, or a summer evening, on whichever side I turn my eyes, myriads of happy beings crowd upon my view. 'The insect youth are on the wing.' Swarms of new-born flies are trying their pinions in the air. Their sportive motions, their wanton mazes, their gratuitous activity testify their joy and the exultation they feel in their lately discovered faculties ... The whole winged insect tribe, it is probable, are equally intent upon their proper employments, and under every variety of constitution, gratified, and perhaps equally gratified, by the offices which the author of their nature has assigned to them.

It is in our genes to understand the universe if we can, to keep trying even if we cannot, and to be enchanted by the act of learning all the way.

It would be an unsound fancy and self-contradictory to expect that things which have never yet been done can be done except by means which have never yet been tried.

Philosophy became a gloomy science, in the labyrinth of which people vainly tried to find the exit, called The Truth.

Science is a mechanism, a way of trying to improve your knowledge of nature. It's a system for testing your thoughts against the universe, and seeing whether they match.

Surely the mitochondrion that first entered another cell was not thinking about the future benefits of cooperation and integration; it was merely trying to make its own living in a tough Darwinian world

The trick in discovering evolutionary laws is the same as it is in discovering laws of physics or chemistry—namely, finding the right level of generalization to make prediction possible. We do not try to find a law that says when and where explosions will occur. We content ourselves with saying that certain sorts of compounds are explosive under the right conditions, and we predict that explosions will occur whenever those conditions are realized.

The trouble about always trying to preserve the health of the body is that it is so difficult to do it without destroying the health of the mind.

There is no fun in psychiatry. If you try to get fun out of it, you pay a considerable price for your unjustifiable optimism.

There must be some bond of union between mass and the chemical elements; and as the mass of a substance is ultimately expressed (although not absolutely, but only relatively) in the atom, a functional dependence should exist and be discoverable between the individual properties of the elements and their atomic weights. But nothing, from mushrooms to a scientific dependence can be discovered without looking and trying. So I began to look about and write down the elements with their atomic weights and typical properties, analogous elements and like atomic weights on separate cards, and soon this convinced me that the properties of the elements are in periodic dependence upon their atomic weights; and although I had my doubts about some obscure points, yet I have never doubted the universality of this law, because it could not possibly be the result of chance.

[Vestiges begins] from principles which are at variance with all sober inductive truth. The sober facts of geology shuffled, so as to play a rogue's game; phrenology (that sinkhole of human folly and prating coxcombry); spontaneous generation; transmutation of species; and I know not what; all to be swallowed, without tasting and trying, like so much horse-physic!! Gross credulity and rank infidelity joined in unlawful marriage, and breeding a deformed progeny of unnatural conclusions!

[Richard P.] Feynman's cryptic remark, “no one is that much smarter ...,” to me, implies something Feynman kept emphasizing: that the key to his achievements was not anything “magical” but the right attitude, the focus on nature's reality, the focus on asking the right questions, the willingness to try (and to discard) unconventional answers, the sensitive ear for phoniness, self-deception, bombast, and conventional but unproven assumptions.

“Try another Subtraction sum. Take a bone from a dog: what remains?” [asked the Red Queen]
Alice considered. “The bone wouldn't remain, of course, if I took it—and the dog wouldn’t remain; it would come to bite me—and I’m sure I shouldn’t remain!”
“Then you think nothing would remain?” said the Red Queen.
“I think that’s the answer.”
“Wrong, as usual,” said the Red Queen, “the dog's temper would remain.”