The great achievements of the past were the adventures of the past. Only the adventurous can understand the greatness of the past.

Human life is driven forward by its dim apprehension of notions too general for its existing language.

Faith in the possibility of science, generated antecedently to the development of modern scientific theory, is an unconscious derivative from medieval theology.

We think in generalities, but we live in detail.

There is no more common error than to assume that, because prolonged and accurate mathematical calculations have been made, the application of the result to some fact of nature is absolutely certain.

But you can catch yourself entertaining habitually certain ideas and setting others aside; and that, I think, is where our personal destinies are largely decided.

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