Heraclitus somewhere says that all things are in process and nothing stays still, and likening existing things to the stream of a river he says that you would not step twice into the same river.

Eyes are more accurate witnesses than ears.

When men dream, each has his own world. When they are awake, they have a common world.

Life is a child moving counters in a game.

There is exchange of all things for fire and of fire for all things, as there is of wares for gold and of gold for wares.

Knowing many things doesn't teach insight.

All things come into being by conflict of opposites.