Heraclitus

"We are most nearly ourselves when we achieve the seriousness of the child at play."

"Nothing endures but change."

"No man ever steps in the same river twice, for it's not the same river and he's not the same man."

"The eyes are more exact witnesses than the ears."

"Much learning does not teach understanding."

"Couples are wholes and not wholes, what agrees disagrees, the concordant is discordant. From all things one and from one all things."

"It is better to hide ignorance, but it is hard to do this when we relax over wine." - fragment

"Character is destiny." - fragment

"There is nothing permanent except change." - quoted by Diogenes Laertius in Lives of the Philosophers

"All is flux, nothing stays still." - quoted by Plato in Cratylus