Intellect is more truly the 'servant' than will or love. Will and love fall on God as being good, and if He were not good, they would ignore Him. Intellect penetrates right up into the essence without heeding goodness or power or wisdom, or whatever is accidental. It does not care what is added to God, it takes Him in Himself, sinks into the essence and takes God as He is pure essence. Even if He were not wise nor good nor just, it would still take Him as pure being. Here intellect is like the highest rank of angels, of which there are three choirs. The Thrones receive God into them and keep God among themselves, and God rests among them; the Cherubim know God and persist therein; Seraphim means 'burning fire. Intellect is like these and keeps God in itself. With these angels the intellect receives God in His robing room, naked, as He is One without distinction.
—Meister Eckhart, Sermon 31, The Complete Mystical Works
Some thoughts about this complex passage.
In this passage, Meister Eckhart gives us intellect as that which contacts God without attributes. That is, it contacts God in His original, unfettered state, shorn of all worldly associations.
Will and love, as he expresses it, want something from God; they want goodness. As such they haven't purified themselves of desires; for to want the good is to have desire. And intellect, as we meet it here, has moved beyond desire. It moves, in point of fact, beyond all known qualities; and this is extraordinary, because it implies a penetration into the transcendent.
Yet the penetration still isn't an entry; rather, that penetration leads to the robing roomn, a vestibule, that is, the place in which God acquires the characteristics that the world of words and concepts assigns to him. Here, there are angels; and the angels receive, know, and burn.
To receive is to be female and take in the generative seed; this is the same action as the birth of the material world from the unknowable soul of God's Being. So the first choir of angels represents the first birth of God into the world. We associate this with the right side of the enneagram and the descent of God's Being into the material plane; yet we also know that this is the realm where Grace acts, and where conscious labor takes place. It is the realm of the prayer "I am—I wish to be." This roughly corresponds to the body of God, or, physical nature.
To know is to be filled with that essential knowing which has no words in it; and this is the left side of the enneagram, which represents the acquisition and purification of Being. It's the realm of the second and most powerful prayer: Lord Have Mercy. It is the place of knowing and is crowned by wisdom. We can also associate this choir with the second conscious shock, intentional suffering. It roughly corresponds to the feeling of God or, emotional nature.
To burn is to be consumed by transcendent fire. This last choir represents the passage from the note si to do; it is the re-entry into God's Being. It roughly corresponds to the mind of God or intellectual nature.
In other words, Meister Eckhart has mirrored here Gurdjieff's concept of three-brained being; and the angelic choruses reflect, as does Swedenborg's three levels of heaven (another close analog) a tripartite interaction of understandings, composed of three separate or distinct languages or modalities. The intellect, here, is a composite entity—as he says of it, it is like the angelic choirs (like these.) So it mirrors and emulates the tripartite action of the choirs, harmoniously; yet it is of itself, interestingly, undivided; that is, it appears to us as a single thing, not a group of three choirs. This indicates an essential otherness that puts it not just at, but slightly above, the properties of the angels. The idea is consistent with other esoteric evaluations of man's position in cosmological hierarchy.
Taken together, the choirs—which by default imply harmony—are equivalent to the intellect; indeed, it has the same stature and waits for God in the same place (the robing room.) This action in this location gives us God in man; and yet, not quite God in man, but man ready to receive God, in that primal moment before the world of objects, events, circumstances and conditions creates the infinite names by which all things are known.