Aristippus being asked what were the most necessary things for well-born boys to learn, said, "Those things which they will put in practice when they become men.

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

That man does not possess his estate, but his estate possesses him.

The mountains too, at a distance, appear airy masses and smooth, but seen near at hand they are rough.

Euripides says,-Who knows but that this life is really death,And whether death is not what men call life?

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

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