"The past is certain, the future obscure."

Thales of Miletus

"I know that I know nothing."

Socrates

"The measure of a man is what he does with power."

Plato

"Do not say a little in many words but a great deal in a few."

Pythagoras

"First, do no harm"

Hippocrates

"What has been affirmed without proof can also be denied without proof."

Euclid

"πάντα ῥεῖ (panta rhei) - everything flows"

Heraclitus of Ephesos

"The difficulty is not so great to die for a friend, as to find a friend worth dying for."

Homer's Iliad

"Nothing exists except atoms and empty space; everything else is opinion."

Democritus

"The whole is more than the sum of its parts."

Aristotle