One of the sayings of Diogenes was that most men were within a finger's breadth of being mad; for if a man walked with his middle finger pointing out, folks would think him mad, but not so if it were his forefinger.

Ignorance plays the chief part among men, and the multitude of words.

As some say, Solon was the author of the apophthegm, "Nothing in excess.

Plato affirmed that the soul was immortal and clothed in many bodies successively.

When asked what learning was the most necessary, he said, “Not to unlearn what you have learned!”

There is a written and an unwritten law. The one by which we regulate our constitutions in our cities is the written law; that which arises from customs is the unwritten law.

Diogenes, when asked from what country he came, replied, "I am a citizen of the world."