“Every revolution was first a thought in one man's mind, and when the same thought occurs to another man, it is the key to that era.”

“By consequence, or train of thoughts, I understand that succession of one thought to another which is called, to distinguish it from discourse in words, mental discourse. When a man thinketh on anything whatsoever, his next thought after is not altogether so casual as it seems to be. Not every thought to every thought succeeds indifferently. ”

“A woman should be mindful that the key to one man's heart does not necessarily fits into the lock of another.”

“Friendship ... is born at the moment when one man says to another "What! You too? I thought that no one but myself . . .”

“To every man is given the key to the gates of heaven. The same key opens the gates of hell. And so it is with science.”

“Indeed, a man is rather being thought than thinking, when a new thought arises in his mind.”