Even the wisest amongst us has no wings to escape himself.

Even when a man stands upright on the tallest mountain and perceives all there is to perceive, comprehends all there is to comprehend, achieves the ultimate realization of the Oneness that lies behind all things, and the nothingness of his own self—

In the end, he is still stuck on the ground where his feet have brought him. His eyes have not seen beyond his own eyeballs; his mind has grasped only that which a mind can grasp and touched that which it can reach. He has remained within his own self.

And the proof:
he has remained with a G‑d who is above
and an earth which is below, and the two cannot meet.

His only liberation, and the only liberation of the entire world, is when the One Above reaches down and tells us, “Do this. With this deed you are betrothed to Me.”

And then there is no above and below.
Then there is only One.