As Heraclitus said, you cannot step into the same river twice.

Everything is change; and you cannot step twice into the same river.

It's said that you can't step into the same river twice.

Every college student who ever struggled through Philosophy 101 knows that you cannot step twice into the same river.

But I know enough not to step in the same river twice.

And yet, as Obama himself said last year, you never step in the same river twice.

It's not every day that you can step into the same plot twice.

But you cannot step in the same river twice, as the philosopher Heraclitus put it.

He said: "You cannot step in the same river twice."

As she writhed, he had to step out of the way twice.