It is natural to think that an abstract science cannot be of much importance in affairs of human life, because it has omitted from its consideration everything of real interest.

The difference between ancients and moderns is that the ancients asked what have we experienced, and moderns asked what can we experience.

How the past perishes is how the future becomes.

The art of progress is to preserve order amid change and to preserve change amid order.

It is a safe rule to apply that, when a mathematical or philosophical author writes with a misty profundity, he is talking nonsense.

Seek simplicity, then distrust.

To be an abstraction does not mean that an entity is nothing. It merely means that its existence is only a factor of a more concrete element of nature.