Conjoined instrument
| Latin | Instrumentum coniunctum |
|---|---|
| Treatise | Summa theologiae III, question 62, article 5; question 8, article 1 |
| Controlling authority | Catechism 470–478 and 1113–1116; Chalcedonian Christology |
| Doctrinal standing | The assumed humanity as living instrument of the Word is Catholic teaching; the technical pair conjoined/separated instrument is Thomistic |
| School | Thomism |
| Branch | Christology and sacraments |
Conjoined instrument is the Thomistic name for the assumed humanity of Christ as the living instrument united to the Word, through which God works salvation, distinct from the sacraments as separated instruments.
Humanity as instrument of the Godhead
The Catechism of the Catholic Church, 470–478, confesses the two natures in the one Person of Christ and the truth of the assumed humanity. Summa theologiae III, question 8, article 1, reply 1, says that to give the Holy Spirit belongs to Christ as God authoritatively, but instrumentally also to him as man, inasmuch as his manhood is the instrument of his Godhead. The humanity is not a mask. It is a true nature that acts, suffers, and is the living tool of the Word.[1][2]
Instrument here does not mean a dead stick. A conjoined instrument is united to the principal agent as the hand is to the man, not as the axe is to the carpenter. The assumed nature has its own operations. Those operations are the operations of the Word because the Person is one. The school term protects both the integrity of the humanity and the unity of the Person.
Separated instruments of the Passion
Summa theologiae III, question 62, article 5, asks whether the sacraments of the New Law derive their power from Christ's Passion. Aquinas answers that they do. Christ's humanity is the conjoined instrument. The sacraments are separated instruments. Water, words, and oil do not become a fourth nature in Christ. They are instituted signs through which the power of the Passion is applied.[3]
The 1913 Catholic Encyclopedia article on the sacraments records this principal-and-instrumental analysis as the classical scholastic account. It is theology. The Church has not defined the word instrumentum. The analysis is the classical reason the rites are not empty signs.[4]
Defined Christology, school causality
Chalcedon and the Catechism close Nestorian division and Monophysite fusion. The humanity is true. The Person is the Word. The Thomistic instrument language is one way of saying how that humanity is causal in the economy without becoming a second person or dissolving into the divinity. Other Catholic theologies may speak of mediation, priesthood, or mystery with less Aristotelian furniture.
What they may not do is deny that Christ's human acts save, or treat the humanity as a mere occasion for a purely divine act that never touches flesh. The conjoined instrument is the school name for the Catholic fact that we are saved by the Word made flesh.
Liturgical consequence
If the humanity is the living instrument, then the mysteries of the life of Christ are not a biography beside the sacraments. They are the source from which the sacraments draw. The priest is not the principal agent. He is a minister of the separated instrument. The holiness of the minister is not the engine. The Head is.[5]
Christ acts in the sacraments. The technical name instrumentum coniunctum is school language. The rites do not work by the congregation's sincerity alone, and the humanity of Christ is not a past event with no present causal reach.
References
- Back to citation Thomas Aquinas, Summa theologiae III, question 8 — Primary treatment of Christ's grace as Head of the Church, capital grace, and the humanity of Christ as instrument of the Godhead.
- Back to citation Catechism of the Catholic Church, 470–478 — Authoritative confession of the two natures in the one Person of Christ and of the assumed humanity in the economy of salvation.
- Back to citation Thomas Aquinas, Summa theologiae III, question 62 — Primary account of the sacraments as instrumental causes of grace, sacramental grace beyond the virtues and gifts, and power derived from Christ's Passion.
- Back to citation Catholic Encyclopedia (1913), Sacraments — Public-domain doctrine of the sacraments as signs that cause grace, with the principal-instrumental analysis.
- Back to citation Catechism of the Catholic Church, 1127–1134 — Authoritative doctrine that the sacraments confer the grace they signify by Christ's own action, working ex opere operato when validly celebrated.