“Travel and change of place import new vigor to the mind.”

“Love is pleasure accompanied by the idea of an external cause, and hatred pain accompanied by the idea of an external cause.”

“Whereof one cannot speak thereof one must be silent.”

“Wisdom begins with wonder.”

“Tries and fields tell me nothing: men are my teachers.”

“Cogito ergo sum. I think, therefore I am.”

“Once spirit was God, then it became man, and now it is even becoming mob.”

“You cannot open a book without learning something.”

“Advice to intellectuals: let no – one represent you.”

“All men, by nature, desire to know.”