By way of illustration: The way that the soul is bound together with the body and fuses with it as though they become one thing; although the body is only the “vessel” for the soul which is the main life and existence of the person, nevertheless, the soul fuses together with the body, thus, the term “Adom-Man” describes the soul as its invested in the body, so that the body does not have an identity for itself, thus, the body becomes an extension of the soul itself, like “the snail, whose ‘garment,’ i.e., shell, grows from its own body,” (see Bereishis Rabbah, 21:5).
Another example: A person who has studied much wisdom is called “a wise man.” Now, before the person learned this wisdom, it existed completely independently of the person who later learned it, and the person existed completely independently of that wisdom.
Still, when the student thoroughly acquires the wisdom, he is now called wise, as a title of the person himself. So too, by way analogy, is the unity Above: that is, although the Keilim of BY”A and the various souls and angels in those realms are an entity of their own, that is seemingly only devoted to servicing Hashem, but not One with him, nevertheless, because the prophets drew down the revelation of Hashem’s Infinite Light to become invested into them like how it is invested in and united with the Keilim of Atzilus, then Hashem is called “הֲוָּיָּ''ה צְבָּאוֹת-Hashem, who is the Master of the Multitudes [of creations],” as a title for Hashem, as it were, since at that point, He becomes One with the “צְּבָּאוֹּת-multitudes” of souls and angels, and they are not separate from Him. Therefore, the Name הֲוָּיָּ''ה can be combined with the Name צְּבָּאוֹּת, together forming the Name “הֲוָּיָּ''ה צְבָּאוֹת-Hashem, who is the Master of the Multitudes.”
