Jacob didn’t know who ambushed him. He assumed it was a man; from Jacob’s view, his assailant could have been anyone —even Esau himself! As the wrestling match continued throughout the night, Jacob finally realized that he was fighting with an angel!
The Midrash identifies the mysterious assailant as the guardian spirit of Esau. The battle between Jacob and the angel represents the archetypal struggle between good and evil. Some Hellenistic Judaic thinkers suggest this entire episode reflected an inner struggle within Jacob’s own soul, and may have even occurred in a dream.
This view was later championed by Maimonides and Gersonides. Both thinkers view Jacob’s struggle with the angel as an example of a visionary experience. God wanted Jacob to know that Esau was not his real enemy, rather, Jacob’s real enemy was himself. The angelic being Jacob wrestled with was really a symbolization of himself. Once he learned to resolve his inner conflict, dealing with Esau would prove quite easy.
There is an art to fighting the inner enemy. The Chinese philosopher Sun Tzu (6th–5th century B.C.E.) and general expressed this idea well, “If you know the enemy and know yourself, you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory gained you will also suffer a defeat. If you know neither the enemy nor yourself, you will succumb in every battle.”
 The Art of War, (ch. 3, Axiom: 4).