The Trinitarian Theology of Saint Thomas Aquinas - El Camino ...

Trinitarian Monotheism 145
What makes the persons of the Trinity plural is not the common essence but
relation as a personal property, a ‘quasi principle of individuation’. One of the
outstanding beneWts of the doctrine of the immanent processions is that its
perception of the origin of the Word and Love in the Trinity shows this: the
Word and Love proceed within the unity of the divine nature. Relative
opposition as to origin makes the relations really distinct from one another,
but each of them is really identical to the single divine essence or substance.86
In sum, this body of ideas (the person, relative opposition, Word and Love,
and subsistent relation), coheres around the depiction of the Trinitarian unity
of God.
5. PERSON AND ESSENCE: A PROBLEM RAISED
BY JOACHIM OF FIORE
Once the controversy created by Gilbert de la Porrée was over, a diVerent
misapprehension led to a more precise articulation of the relation between the
Trinity and Unity of God. It came about in Joachim of Fiore’s polemics
against Peter Lombard. Peter Lombard’s Sentences take up a radically diVerent
position on this from what we described earlier as being Roscelin’s stance.
Doubtless with Gilbert de la Porrée in mind, the Lombard aYrmed the
absolute prerogatives of the unity of God: the Triune God is ‘a single, onceoV
supreme reality’.87 Since the divine essence is an ‘unitary, sovereign reality’,
Peter Lombard refuses to accept formulae like ‘the Father engenders the
divine essence’, or ‘the divine essence engenders the Son’. Since the essence
or divine substance is the unitary reality of the Triune God, Peter Lombard
Wgured that one cannot say the essence engenders, or is engendered, or
proceeds: this would mean that the essence engenders itself, that is, that the
Trinity engenders itself. It does not belong to the essence or to the substance
but to the person to be the subject of generation and procession.88
This understanding of the three persons aroused both deep incomprehension
and steely opposition in Joachim of Fiore (þ1202). Joachim was attached
to diVerent formulae from these, which did use the words ‘substance’ or
‘essence’ to mean the person or hypostasis (and patristic precedents for
these are not uncommon). So he rejected the terminology which Peter
Lombard had imposed. Failing to grasp the way the Lombard’s analysis
86 ST I, q. 29, a. 4; cf. q. 28, a. 2.
87 Peter Lombard, Sentences, book I, dist. 25, ch. 2, n. 5 (vol. I/2, p. 194).
88 Peter Lombard, Sentences I, book I, dist. 5, ch. 1 (vol. I/2, pp. 80–87).