Descartes constructed as noble a road of science, from the point at which he found geometry to that to which he carried it, as Newton himself did after him. ... He carried this spirit of geometry and invention into optics, which under him became a completely new art.

He is lifeless that is faultless.

We only half live when we only half think.

What most persons consider as virtue, after the age of 40 is simply a loss of energy.

Liberty of thought is the life of the soul.

I die adoring God, loving my friends, not hating my enemies, and detesting superstition.

In this country we find it pays to shoot an admiral from time to time to encourage the others.