If thou continuous to take delight in idle argumentation thou mayest be qualified to combat with the sophists, but will never know how to live with men.

Nobody knows anything, but I, knowing nothing, am the smartest man in the world.

Prefer knowledge to wealth, for the one is transitory, the other perpetual.

Are not all things which have opposites generated out of their opposites?

Bad men live that they may eat and drink, whereas good men eat and drink that they may live.

And the same things look bent and straight when seen in water and out of it, and also both concave and convex, due to the sight's being mislead by the colors, and every sort of confusion of this kind is plainly in our soul. And, then, it is because they take advantage of this affection in our nature that shadow painting, and puppeteering, and many other tricks of the kind fall nothing short of wizardry.

All that I know is nothing - I'm not even sure of that.