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.

The path up and down is one and the same.

The sun is new each day.

You won't discover the limits of the soul, however far you go.

You may travel far and wide but never will you find the boundaries of the soul.

If you do not expect the unexpected, you will not recognize it when it arrives.

Knowing many things doesn't teach insight.