The worst thing you can possibly do is worrying and thinking about what you could have done.

We are obliged to regard many of our original minds as crazy at least until we have become as clever as they are.

Prejudices are so to speak the mechanical instincts of men: through their prejudices they do without any effort many things they would find too difficult to think through to the point of resolving to do them.

How might letters be most efficiently copied so that the blind might read them with their fingers?

So-called professional mathematicians have, in their reliance on the relative incapacity of the rest of mankind, acquired for themselves a reputation for profundity very similar to the reputation for sanctity possessed by theologians.

Nothing reveals a man's character better than the kind of joke at which he takes offense.

Never undertake anything for which you wouldn't have the courage to ask the blessings of heaven.