Theologicae regulae

Monad begets monad, and reflects its own ardor back into itself.

This rule arises from the one before: for it has been said that God is called a monad for this reason, that from himself he begets God, from himself also he produces the Holy Spirit, just as unity of itself begets unity. Monad, therefore, begets monad, that is, the Father the Son: for it was necessary that if a monad should beget, it should beget a monad: for nothing can be begotten from a simple thing by division, as happens in natural generation. It was necessary, then, either that nothing be begotten from the simple, or that a simple thing be begotten from the simple. Whence Augustine says that the Father poured his whole substance into the Son, because he is not of the same substance with the Father by division, but by the fullness of nature. And because the Holy Spirit proceeds from the Father and the Son, it follows: And reflects its own ardor back into itself. The Holy Spirit is called ardor, love, kiss, and connection of the Father and the Son, because the Father spiritually agrees with the Son in breathing forth the Holy Spirit. And because in the gifts of the Holy Spirit, which are given by the Father and the Son, their love toward us is signified, because the production of the Holy Spirit from the Father and the Son is a certain signification of the love of the Father and the Son, that is, the unity of both; for unless they agreed in one nature, they would not breathe forth by one breathing: this is called the ardor, or love, of the Father and the Son. This ardor, then, proceeds from the monad, that is, from the Father, in such a way that it does not desert him, because it is of the same essence with him; or it reflects its own ardor into another, that is, into the Son, that is, the Holy Spirit; but it proceeds from the Father in such a way that it proceeds by his authority from the Son.