Theologicae regulae

In the supercelestial, unity; in the celestial, otherness; in the subcelestial, plurality.

The supercelestial is God, in whom there is supreme unity. The celestial is the angel, in whom there is first otherness, because he is the first created by God, and the first made mutable after God: yet he is not said to have as much variety as the subcelestial has. Whence, because otherness is the first plurality, in him it is not said to be plurality, but only otherness. In the subcelestial, however, as in these corporeal things, full plurality is said to exist, because it is subject to manifold variety. Wherefore truly God is one, or unity, by reason of simplicity, by reason of immutability, by reason of exclusion, by reason of likeness: therefore the monad alone is, that is, God alone truly exists, that is, simply and immutably a being; but other things truly are not, because they never remain in the same state. Here follows the end of the first rule, by which any thing is one. For nothing is one by any species of unity that is not one from the supreme monad. For there is a unity of singularity, according to which anything is said to be one in number. Whence Boethius: "Whatever is, is therefore, because it is one in number; and whatever, in this unity, is one, has it from that source that it is one." There is a unity of union, according to which many men are said to be one, not from unity, but from union; and this too is from God: whence also the authority testifies concerning John: "All things were made through him," etc.¹ All concord is from God. There is also unity of distinction, or discretion, which draws its origin from the same source. For whatever is discrete or distinct is from God. There is also unity of integrity, which consists in the composition of parts, according to which a man is said to be one, that is, integrated from soul and body, is from God. Whence the authority: "Every joining together is from God." There is also unity of adunation, according to which many men, coming together under the same law of living, and placed under the yoke of the same law, are said to be one people, is from God. There is unity of consensus, according to which it is said: "They had one heart and one soul,"² is from God.