Unity of God and Oneness of God (The Difference Between Them)

In his enumeration of commandments, Rambam counts the commandment of Unity of God and the commandment of Knowledge of God as two separate commandments.

The Difference Between Them According to the Revealed Teachings

The commandment of Unity of God concerns knowledge of God's existence, and its essence is to believe that God's existence is simple oneness. That is, not a oneness that can be counted, nor a oneness that is composite.

The commandment to unify Him is to believe that all the descriptions attributed to Him by the Torah (under His feet, written by the finger of God, the eyes of God, the ears of God, and similar expressions) are only to make it comprehensible to human understanding, as "the Torah speaks in human language," because people only recognize physical bodies.

The Difference Between Them According to Chassidism

The Commandment of Knowledge of God

According to Chassidism, this commandment is not limited to believing that there is no other deity besides God (and that He is one, unique, and singular), but that there is nothing whatsoever besides Him, that there is no existence apart from Him at all. We must believe and know that in truth, all created beings are nullified in existence at their source and root, and the fact that they appear to exist is only in their perception (since the divine power that brings them from nothingness to existence is hidden from them).

This profound interpretation simply explains why the Torah demands "You shall know this day and take it to heart that Hashem is God in the heavens above and on the earth below, there is none other." This verse implies that understanding this concept is difficult—but why? Because understanding and internalizing this concept (that there is no existence besides God) contradicts intellect and human emotion, belief in this requires deep understanding and lengthy contemplation until it is internalized in the heart.

This understanding raises several difficult questions about the fundamentals of faith, and the Alter Rebbe answers all of them with great clarity.

The Commandment to Unify Him

"To unify Him" means "to make" Him one. Not just to believe that He is one but to "effect" His oneness. This is why we say at the beginning of each day "For the sake of the unification of the Holy One, blessed be He, and His Shechinah"—that the entirety of all service is "to unify His name." That is, God desired to create the world so that He would have "a dwelling in the lower realms": He created a world of "lower realms" (where divinity is concealed and hidden), and our task is to make for Him within it "a dwelling"—"to unify His name": that in the world (as it is limited in the lower constraints of time and space) the divine truth of "there is nothing besides Him" should be revealed.

In this unification there are two ways—"Hear O Israel, Hashem is our God, Hashem is One" is the higher unification (Yichuda Ila'ah), and "Blessed is the name of His glorious kingdom forever and ever" is the lower unification (Yichuda Tata'ah).

Yichuda Ila'ah (Higher Unification)

Yichuda Ila'ah is "Hashem is One"—although we are speaking of "seven heavens and earth and the four directions of the world," they are all nullified to the "Master of the world"—the world is elevated to a level where it is completely nullified to divinity. In Chassidic teaching, three examples are given for this:

a. In the Holy Temple - "The place of the Ark was not included in the measure." The limited physical world is elevated until the divine light shines within it in complete revelation, and it is completely nullified to it. There is an "Ark" and there is a "measure"—and yet simultaneously neither it nor its measure take up space. Finite and infinite in one place.

b. In the world - Miracles that transcend nature. Nature exists, it is seen and felt in its full existence (there is water, and it is liquid and wet)—but it behaves in a divine manner that is above nature (it stands like a wall).

c. In the person - During prayer, a person rises above his concerns and is completely nullified to God. His heart continues to work, and he breathes and lives—but his entire essence and existence are nullified to God, until he stands without movement and without utterance and asks "O Lord, open my lips and my mouth will declare Your praise"—as he is not even an existence that can open his mouth.

Yichuda Tata'ah (Lower Unification)

Yichuda Tata'ah is "forever and ever." The letter aleph of echad (one) descends from its level and is replaced by the letter vav (of va'ed), the letter chet descends and is replaced by the letter ayin, and the large letter dalet of echad is replaced by a regular medium-sized dalet. In a certain sense, the purpose of this unification is the opposite of Yichuda Ila'ah: not that the world is elevated to divinity, but that divinity descends and is revealed within the existence of the world and the person. That is, the person engages in business literally—but does so "in faith." An observer from the side sees only the dimensions of the world (a person engaged in commerce), but the person himself is nullified to divinity and conducts himself according to its light. At this level, what is primarily felt is not divinity but the world, except that even as the world is limited and defined in the most physical and lowest manner, it is directed by the Infinite Light.