Xenophanes speaks thus:-And no man knows distinctly anything,And no man ever will.

Heraclitus says that Pittacus, when he had got Alcæus into his power, released him, saying, "Forgiveness is better than revenge.

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

If appearances are deceitful, then they do not deserve any confidence when they assert what appears to them to be true.

The sun too penetrates into privies, but is not polluted by them.

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

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