Quoting: Plato (427 BC - 347 BC)

[onomatopoeias]

Necessity, who is the mother of invention.
-Plato, The Republic

Wise men talk because they have something to say; fools, because they have to say something.
-Plato

One of the penalties for refusing to participate in politics is that you end up being governed by your inferiors.
-Plato

Courage is knowing what not to fear.
-Plato

I was afraid that by observing objects with my eyes and trying to comprehend them with each of my other senses I might blind my soul altogether.
-Socrates, In "Phaedo," sct. 98, by Plato

If one has made a mistake, and fails to correct it, one has made a greater mistake.
-Plato