Chapter 26 — That there are no more than three persons in God: the Father, the Son, and the Holy Spirit

We gather from what has been said in the preceding chapters that in the divine nature there subsist three persons, Father, Son, and Holy Spirit; and that these three are one God, being distinct in relations alone. The Father is distinct from the Son by the relation of paternity, and by innascibility; the Son from the Father, by the relation of sonship; the Father and the Son from the Holy Spirit by spiration, as it may be called; and the Holy Spirit from Father and Son, by the procession of love, whereby he proceeds from both.

Besides these three persons, there is no fourth in the divine nature. Since the divine persons agree in essence, they cannot be distinct save by relations of origin, as we have already made clear. (Ch. 24.) Now these relations of origin do not arise from a procession tending to external things (for thus the thing that proceeds is not of the same essence as its principle), but from a procession that remains within. And it is only in the working of the intellect and will that a thing is found to proceed so as to remain within its principle, as we have explained. (Ch. 11.) Therefore, the divine persons cannot be multiplied except insofar as this is necessitated by the processions of intellect and will in God. Now in God there can be only one procession according to the intellect, because his act of intelligence is one, simple and perfect. For in understanding himself, he understands all things else, so that in God there can be but one procession of the word. In like manner, there can be but one procession of love, since the divine volition is one and simple, because in loving himself, he loves all other things. Consequently, in God there can be no more than two proceeding persons: one by way of intelligence, as word, namely the Son; the other by way of love, namely the Holy Spirit. There is also one person who does not proceed, namely the Father. Therefore, there are but three persons in the Trinity.

Again. The persons are distinguished according to procession. Now in respect of procession, there are but three modes possible in a person: either he proceeds not at all, like the Father; or, as the Son, he proceeds from one that does not proceed; or, like the Holy Spirit, he proceeds from one who proceeds. Therefore, there cannot be more than three persons.

And although, in other living beings, relations of origin can be multiplied—thus in human nature there can be many fathers and many sons—in the divine nature this is quite impossible. For, since in one nature filiation is of one species, it cannot be multiplied except in respect of its matter or subject, as in the case of other forms. Hence, as in God there is no matter or subject, and as the very relations are subsistent (as we have proved), (Ch. 14.) there cannot be several filiations in God. The same applies to the other relations. Thus in God there are but three persons.

Someone may object that since the Son is perfect God, he has perfect intellectual power, and consequently he can produce a word; and in like manner, as there is infinite goodness in the Holy Spirit whereby he is the principle of the communication of goodness, he will be able to bestow the divine nature on another. To this we reply that the Son is God as begotten, and not as begetting. Hence the intellectual power is in him as in one proceeding by way of word, and not as in the one producing the word. In like manner, since the Holy Spirit is God as proceeding, infinite goodness is in him as the recipient, and not as communicating the infinite goodness to another. For they are not distinguished from one another except by the relations alone, as we have shown. Hence the whole fullness of the divinity is in the Son, identically the same as that which is in the Father. But in the Son it is with the relation of birth; in the Father, with the relation of active generation. Thus, if the Father’s relation were ascribed to the Son, there would no longer be any distinction between them. And the same applies to the Holy Spirit.

We may now consider the likeness to the divine Trinity in the human mind. The mind, by actually understanding itself, produces its word within itself. This word is the intelligible reflection of the mind, and is called the idea existing in the soul, and when it loves itself, it reproduces itself in the will as loved. Further than this, it does not proceed within itself, but completes the circle, when by love it returns to the very substance from which the procession began in the idea. There is, however, a procession towards external effects, when through love of self one proceeds to action. Thus there are three things in the mind: the mind itself in its natural existence (which is the starting-point of the procession); the conception of the mind in the intellect; and the mind loved in the will. Yet these three are not one nature, since the mind’s act of intelligence is not its being; and its volition is neither its being nor its act of intelligence. For this reason the mind understood and the mind loved are not persons, since they are not subsistent: nor is the mind a person in its natural existence, for it is not the whole subsistence, but only part of the subsistence—that is to say, of man.

Accordingly, in our mind there is a likeness to the divine Trinity as regards the processions which multiply the persons. For we have sufficiently shown that in the divine nature there is God unbegotten, namely the Father, who is the principle of the whole divine procession; God begotten, as the word is conceived in the intellect, and this is the Son; and God proceeding as love, who is the Holy Spirit. There are no further processions within the divine nature, but only those that terminate in external effects. This likeness, then, falls short of being a representation of the divine Trinity, in that Father, Son, and Holy Spirit are of one nature, and each of them is a perfect person, since God’s very being is intelligence and will, as we have shown. Hence the divine likeness is reproduced in man in respect of the form represented, as the likeness of Hercules is reproduced in stone, but not by community of nature. Therefore, God’s image is stated to be in the human mind: Let us make man in our image, after our likeness (Gen 1:26).

In other things also there is a likeness to the Trinity inasmuch as each thing is one in its substance, informed by a certain species, and has a certain order. Now, as we have already clearly stated, the intellectual concept in intelligible being is like the information of the species in natural being, and love is like the inclination or order of a natural thing. Thus in natural things species represents the Son remotely, and order represents the Holy Spirit. Hence, on account of the likeness in irrational things being remote and obscure, we say that there is in them a trace but not an image of the Trinity: Perhaps you will understand the traces of God (Job 11:7).

For the present, we have said enough about the Trinity.

The Incarnation