“Nothing is duller than a progression of common chords. One wants some contrast, which breaks up the clear white light and makes it iridescent.”

“A nation which thinks that it is belief in God and not good law which makes people honest does not seem to me very advanced.”

“You live as if you were destined to live forever, no thought of your frailty ever enters your head, of how much time has already gone by you take no heed. You squander time as if you drew from a full and abundant supply, so all the while that day which you bestow on some person or thing is perhaps your last. You have all the fears of mortals and all the desires of immortals… What foolish forgetfulness of mortality to defer wise resolutions to the fiftieth or sixtieth year, and to intend to begin life at a point to which few have attained.”

“As long as the centuries continue to unfold, the number of books will grow continually, and one can predict that a time will come when it will be almost as difficult to learn anything from books as from the direct study of the whole universe. It will be almost as convenient to search for some bit of truth concealed in nature as it will be to find it hidden away in an immense multitude of bound volumes.”

“From fanaticism to barbarism is only one step.”

“The best order of things, as I see it, is the one that includes me; to hell with the most perfect of worlds, if I'm not part of it.”

“Nous aimons, sans nous en douter, tout ce qui nous livre à nos penchants, nous séduit et excuse notre faiblesse.”