Heraclitus

If it were not for injustice, men would not know justice.

Abundance of knowledge does not teach men to be wise.
Heraclitus - On the Universe
You could not step twice into the same river; for other waters are ever flowing on to you.
Heraclitus - On the Universe
Much learning does not teach understanding.
Heraclitus - from Diogenes Laertius, Lives of Eminent Philosophers
All is flux, nothing stays still.
Heraclitus - from Diogenes Laertius, Lives of Eminent Philosophers
Nothing endures but change.
Heraclitus - On the Universe
Nature is wont to hide herself.
Heraclitus - On the Universe
It is better to hide ignorance, but it is hard to do this when we relax over wine.
Heraclitus - In Plato, Cratylus
You cannot step twice into the same river.
Heraclitus - On the Universe
The road up and the road down is one and the same.

Nothing endures but change.

- Heraclitus