Nothing inspires more reverence and awe in me than an old man who knows how to change his mind.

I would be the last to deny that the greatest scientific pioneers belonged to an aristocracy of the spirit and were exceptionally intelligent, something that we as modest investigators will never attain, no matter how much we exert ourselves. Nevertheless ... I continue to believe that there is always room for anyone with average intelligence ... to utilize his energy and ... any man could, if he were so inclined, be the sculptor of his own brain, and that even the least gifted may, like the poorest land that has been well-cultivated and fertilized, produce an abundant harvest.

To know the brain...is equivalent to ascertaining the material course of thought and will, to discovering the intimate history of life in its perpetual duel with external forces.

The worst part is not in making a mistake but in trying to justify it, instead of using it as a heaven-sent warning of our mindlessness or our ignorance.

The brain is a world consisting of a number of unexplored continents and great stretches of unknown territory.

Nothing inspires more reverence and awe in me than an old man who knows how to change his mind.

If a solution fails to appear ... and yet we feel success is just around the corner, try resting for a while. ... Like the early morning frost, this intellectual refreshment withers the parasitic and nasty vegetation that smothers the good seed. Bursting forth at last is the flower of truth.