It could not proceed from another person, because, as we have remarked, this other person, unless subsisting of himself, would require another as his principle, and so on ad infinitum.
As a corollary of this law, it follows that whatever other persons may be supposed to exist in the infinite, they must originate from the first; because—no other distinction being possible in the infinite, but that arising from opposition of origin—it follows that, if there were other persons in the infinite, and if they did not originate from the first, they could not be opposed to it, and therefore they could not be distinguished from it; in other words, they could not exist.
A third law governs the life of the infinite; which, if possible, is yet more important than the former two. It is the law of immanence, which may be expressed in the following formula.
The action, by which the persons in the infinite are originated, terminates inside of the infinite, and is permanent, eternal, and complete.
Let it be observed that the action of an agent is always interior to it, because it is its own movement. But the product of the agent is not always so; sometimes it is laid inside the agent; sometimes it terminates outside the agent. In the first case, the action is called immanent or interior; in the second, transient or exterior; not because the action is not always interior to the subject, but because the effect or term of the action is exterior or foreign to the subject. The first sense, then, in which the law of immanence is to be applied to the infinite is, that the terms of the action of the first person terminate inside the infinite; because, if they were to terminate outside of God, they would be something different from him, and consequently not divine persons, but finite beings.
But the law has a higher and more important bearing: it implies that the action by which the divine persons are originated is not transitory, successive, and incomplete, but permanent, eternal, and complete; because God is infinite actuality, or actuality itself.
Forget for one single moment to apply this law to the genesis of God's life, and you fall at once into pantheism. For suppose the act, by which the divine persons are originated, to be transient, successive, temporary, incomplete, and it would follow at once that God is in continual development and explication. For He is either complete and perfect, or on the road to perfection. He is in fieri, or becoming.
And since, as we have often remarked, every development consists of different stages of explication, the last of which is always more perfect than those which precede it, it would follow that the genesis of God's life consists of a successive series of evolutions, the last of which is always more perfect than that which precedes it. Now, assuming the genesis of God's life at one determinate stage, and travelling backward to arrive at the first stage of explication from which He started, we should pass from a more perfect, defined, concrete stage of development, to one less perfect, less defined, less determinate, and thence to one still less so, until we should arrive at the most indeterminate, undefined, abstract stage of evolution; at the least being—the being not being, the first principle of pantheism.
But, keeping in view the law of immanence, every one can see that God's action is supposed at once all perfect, complete, and adequate—in one word, eternal; and consequently every idea of development, progress, and succession is eliminated; and the consequence is, that the infinite is at once conceived as being infinite actuality; the first principle of Catholic theology—the precise contradictory of pantheism.