Xenocrates, aka Xenocrates of Chalcedon

Each man's soul is his genius.

Geometry is one of the handles of science and philosophy.

Go away, you give philosophy nothing to catch hold of.

Happiness is the possession of the excellence proper to us, and of the power subservient to it.

I have often regretted my speech, never my silence.

I have often repented speaking, but never of holding my tongue.

If the ox could think, it would attribute oxality to God.

One may as well go, as look into another man's house; because the eye may reach what the hand cannot.

Antipater uses us favorably if he looks upon us as staves, but very hardly if he considers us as freemen.

Counsel in trouble gives small comfort when help is past remedy.

An ambassador should study the welfare of his country, and not spend his time in feasting and riot.

Men may commit theft as well as adultery with the eye.