Trinitarian Christology of St Thomas Aquinas (Legge)

Not open for further replies.


Puritanboard Clerk
Legge, Dominic., O.P. The Trinitarian Christology of St Thomas Aquinas. New York: Oxford University Press, 2018.

There are a few theology books which demonstrate complete mastery of a field. These are the books that you keep nearby and treat as manuals. Richard Muller’s scholastic dictionary is one. This is another. Far from being a survey of Thomas Aquinas’s Trinitarianism, we get the grammar of how we are supposed to speak of the Trinitarian processions and missions. In a previou review I had said Matthew Barrett’s book on the Trinity was a near-perfect book. Legge’s book is perfect.

Legge unpacks what Thomas means by processions and missions (sending). According to him, “The eternal processions ground both the exitus of the creatures from God and the reditus of creatures to God” (Legge 12). Legge sees the eternal processions as a “path” of our return to the Father.

Legge gives us some groundwork on what is meant by procession and mission. A mission involves two relations: one is the relation of one sent to him from whom he is sent; another is the relation of the one sent to the terminus” (Thomas Aquinas ST 1 43.a.1). A procession, on the other hand, is an immanent act within God that remains in God.

Key idea: “The eternal processions of both the Son and the Holy Spirit are the origin, ratio, cause, and exemplar of our return to the Triune God in the dispensation of grace” (Legge 17).

Another difference between a divine mission and an eternal procession is that the former includes a created effect. This is the temporal aspect. It is the sending of a divine person as really present in time. A mission relates “to a divine person in a new mode” (18). The divine person is the effect’s terminus. There is now a created effect, a relation of reason, between the divine person and the creature.

The divine mission is how the divine person’s eternal procession is made present in the creature.

From here he notes how an invisible mission is “the sending of a divine person to a human being (or an angel) ‘through invisible grace’ and signifies a mode of that person’s indwelling” (25). This involves a habitual grace, a quality of the soul, which acts as a formal, not efficient, cause. Habitual grace is related to the essence of the soul as infused virtues are related to the powers of the soul (28). Legge notes that habitual grace elevates the nature of the soul while the virtues perfect the powers of the soul (29).

Habitual Grace and Causality

Efficient causality: the three Persons are the singular principle of habitual grace.

Exemplar causality: This is the pattern of what comes forth from the processions. This is how the soul is assimilated “to a likeness of the divine persons” (39).

Final causality: in a wonderful phrase, Legge notes that “the gifts of charity and wisdom act as vectors that lead us or bear us back to the whole Trinity” (39).

Summary: “God’s efficient causality, common to all three persons, is shaped by the pattern of the Trinitarian processions...and thus it impresses on the creature an effect that bears the distinctive marks of divine persons” (43-44).

The Hypostatic Union

Aquinas’s account of the hypostatic union is valuable for the attention it gives to the terms “assumption” and “terminus.” According to Legge, the “act of assuming proceeds from the divine power (common to all three persons) but terminates on the Son” (104). This allows Thomas to say that God has a relation with his creatures without making it an essential relation. The relation is a vector into the divine person (105).

We also need to keep in mind the subtle nuance of the term “esse.” It is an act of being, not being qua being. Christ’s humanity has a secondary act of being. The being of the three persons is identical; their mode of being is distinct...The personal property designates the relational mode of being proper to each person” (109).

Key quote: The Trinitarian processions are the vectors of our return to God” (120).

Habitus and Grace

Key question: is Christ holy by virtue of the union or by habitual grace? Our initial answer is that Christ is made formally holy by the same grace by which he justifies, namely, his fullness of habitual grace” (141). This safeguards the numerous Scriptures that say he was anointed with the Holy Spirit.

The grace of union signifies the invisible mission of the Son while habitual grace signifies the invisible mission of the Holy Spirit (148). The former orders and structures the latter. Habitual grace is a created effect. It is how the divine persons are made present in man according to their distinct modes (e.g., the Son as Wisdom; Holy Spirit as charity, etc.).

Christ’s human nature needs a habitus to dispose him to act. Christ’s habitus was perfect from the beginning. It did not increase. The visible effects, however, did (167).

Christ’s Human Knowledge

This is fairly standard Thomism. Christ’s human soul has an immediate vision of God in the highest (Rational) part of the soul. Human nature needed to receive something in that human nature so that his soul can see the essence of God. This is a habitus of divine light (178 n22).

Christ also has an infused knowledge. It is a supernatural gift infused in Christ’s intellect. Christ as man knows all that man is capable of knowing. This is analogous to prophetic knowledge, albeit perfectly. This is known through the gifts of the Holy Spirit.


I cannot praise this book highly enough. It does assume some technical knowledge of Thomas Aquinas, so that is the only thing keeping it from the moniker of “greatest Christology book ever.”
Not open for further replies.