A conceptual scheme is never discarded merely because of a few stubborn facts with which it cannot be reconciled; a conceptual scheme is either modified or replaced by a better one, never abandoned with nothing left to take its place.

Whether a man lives or dies in vain can be measured only by the way he faces his own problems, by the success or failure of the inner conflict within his own soul. And of this no one may know save God.

A conceptual scheme is never discarded merely because of a few stubborn facts with which it cannot be reconciled; a conceptual scheme is either modified or replaced by a better one, never abandoned with nothing left to take its place.

Behold the turtle. He makes progress only when he sticks his neck out.

Science advances, not by the accumulation of new facts, but by the continuous development of new concepts.

Therefore, a grotesque account of a period some thousands of years ago is taken seriously though it be built by piling special assumptions on special assumptions, ad hoc hypothesis [invented for a purpose] on ad hoc hypothesis, and tearing apart the fabric of science whenever it appears convenient. The result is a fantasia which is neither history nor science.

There is only one proved method of assisting the advancement of pure science-that of picking men of genius, backing them heavily, and leaving them to direct themselves.