With toil and persistence, asceticism and great sacrifice, a human being can enlighten his mind. He can reach so high as to perceive the world of the angels—or even to be granted the gift of prophecy.

But, as hard as any of us may try, as long as our brains are made of gray matter, we can never attain the enlightenment of the least of those fiery beings.

What amazes the angels, however, is this uncanny ability of a human being: To stick his head in the clouds and yet keep both feet on the ground. To traverse worlds.

Likutei Sichot vol. 15, pg. 15.