But by far the greatest obstacle to the progress of science and to the undertaking of new tasks and provinces therein is found in this-that men despair and think things impossible.

Many a man's strength is in opposition, and when he faileth, he grows out of use.

Virtue is like a rich stone, best plain set.

The noblest works and foundations have proceeded from childless men, which have sought to express the images of their minds where those of their bodies have failed.

We cannot command Nature except by obeying her.

If I sit and daydream, the images rush by like a succession of colored slides.

Knowledge is power.