Moses, in this week’s Parasha portion, teaches a fundamental principle of Torah philosophy.
“Man does not live on bread alone, but by everything that emanates from G-d does humanity live… you shall eat, be satisfied and bless G-d.” The Zohar, the source of Jewish mystical thought, teaches that nothing in the world could exist without it having a nucleus of G-dliness within it.
Prior to creation, there was nothingness and it was creation that brought matter into existence. Therefore, the natural state is one of nothingness, and G-d must continue to maintain all matter because it was created out of nothingness and would therefore return to non-existence if G-d removes Himself from them. For this reason, all creation continues to exist because it contains a part of the Eternal.
Therefore, when one eats food, the physical body is nurtured by the physical components of the food, while the person’s spiritual component is nurtured from the Divine nucleus, the spiritual force within. Food’s physical nutrients are absorbed through eating and digesting, the absorption of the spiritual component is through the recital of the blessing, where we affirm our recognition of G-d as being the source of everything, and express gratitude towards Him for providing our needs.
This, then, is the meaning of Moshe’s statement. Humanity does not survive only because of the physical nutrients of his food, but by the Divine part within it, who’s nourishment we receive through our blessing.