The Blessed Trinity

Opens Part I and Chapter I of the treatise, then surveys the Old Testament evidence for the Trinity: the divine plurals of Genesis, the Angel of Jehovah theophanies, the Messianic prophecies and psalms, the teaching of the Sapiential Books on Hypostatic Wisdom, and the more obscure Old Testament references to the Holy Ghost. Concludes that the Trinity is foreshadowed, but not clearly revealed, in the Old Testament.

Surveys the New Testament texts that name all three Divine Persons together: the Gospel texts (the Annunciation, the Baptism of Christ, the farewell discourse, and the baptismal formula) and the Epistles (the benediction of 1 Peter, the blessing of 2 Corinthians, the charismata of 1 Corinthians 12, and the Comma Ioanneum), followed by an extended excursus on the textual and dogmatic authenticity of the Comma Ioanneum in light of the 1897 Holy Office decree.

Opens Section 3, which will prove of each Divine Person severally (1) His reality as against mere personification, (2) His non-coincidence with the others as against Sabellianism, and (3) His Divinity as against Arianism and Macedonianism. Article 1 then distinguishes God's merely figurative fatherhood — as Creator, Provider, and adoptive Father of the justified — from His Fatherhood in the strict and proper sense, grounded in the eternal generation of the Son, which makes Him the First Person of the Blessed Trinity.

Opens Article 2 (Of God the Son) and establishes subsection A: that Christ's Sonship is not the merely metaphorical or adoptive sonship shared by creatures, but a true Sonship in the strict sense, attested by the Synoptics, St. John, and St. Paul, and grounded in Christ's consubstantiality — 'form of God,' 'brightness of his glory,' 'firstborn of every creature' — with the Father.

Begins subsection B, proving Christ's Divinity from Scripture in three groups of texts. Covers the first two: (1) Christ's possession of the divine attributes — self-existence, incomprehensibility, truth, life, immutability, eternity, omnipresence, omniscience, cardiognosis, and foreknowledge of free future events — and (2) Christ's title to divine honors — the worship, faith, hope, and charity Scripture accords Him, and His inclusion with the Father and the Holy Ghost in the formula of Baptism.

Completes subsection B by showing that Christ is identified with the Old Testament Yahweh (Hebr. I, 6 with Ps. XCVI, 7; Is. VI with John XII, 41; Mark I with Malachias III) and is expressly called 'God' in at least four New Testament texts: Thomas's confession (John XX, 28), Titus II, 13, 1 John V, 20, and the doxology of Romans IX, 5 — closing with the observation that Christ's more usual New Testament title is 'Lord' (Kyrios), corresponding to the Hebrew Tetragrammaton.

Concludes Article 2 (Of God the Son) with subsection C: the Johannine prologue shows the Logos to be a real Person (not a mere personification of an attribute), a Person distinct from the Father, and Himself God — Creator of all things, eternal, and the source of adoptive sonship and grace. Closes with the Article's bibliography.

Completes Section 3 by proving, from Scripture, that the Holy Ghost is (A) a real Person and not a mere personification of divine power or influence, (B) hypostatically distinct from both the Father and the Son (the Ephesian disciples of John the Baptist; Christ's farewell discourse; the Holy Ghost's procession from the Father), and (C) truly God, possessing the divine attributes, entitled to divine worship, and identified with God in Scripture. Closes with the ordo subsistendi of the Three Divine Persons.

Opens Chapter II by classifying the two ways the dogma of the Trinity can be perverted — Monarchianism (per defectum, exaggerating unity) and Tritheism (per excessum, exaggerating threeness) — and Monarchianism's three historical phases: crass Monarchianism, Sabellian Modalism, and Subordinationism. Article 1 then treats crass Monarchianism in its Dynamistic form (Theodotus of Byzantium, Paul of Samosata) and its Patripassian form (Noetus, Praxeas, Photinus), and its condemnation by Popes Victor I and Callistus and the Council of Antioch, A.D. 269.

Treats Sabellius's Modalism — a merely external, transitive Trinity of manifestation (Father as Creator, Son as Redeemer, Holy Ghost as Sanctifier) rather than a real, immanent Trinity of Persons — and traces its condemnation from Pope Callistus's excommunication of Sabellius through Bishop Dionysius of Alexandria's overcorrection into apparent Ditheism and Pope Dionysius's epoch-making corrective epistle, which first put into circulation the term homoousios later used at Nicaea.

Treats Subordinationism in its two historical phases — Arianism, which denied the Son's coeternity and consubstantiality with the Father, and Macedonianism, which extended the same denial to the Holy Ghost — and its condemnation at the Councils of Nicaea (325) and Constantinople (381), including the full text and analysis of the Nicene Creed's homoousios clause and anathemas, and the Constantinopolitan definition of the Holy Ghost's divinity.

Opens Section 2 by distinguishing Ante-Nicene from Post-Nicene patristic witnesses, then documents the Trinitarian faith of the early Church as expressed in the Apostles' Creed, the Didache's baptismal formula, the private symbol of St. Gregory Thaumaturgus, the ancient doxologies (Gloria Patri, in both its coordinative and subordinative forms), and the dying confessions of the martyrs Polycarp, Epipodius, Vincent, and Euplus.

Documents the clear Trinitarian witness of the Ante-Nicene Fathers, East (Ignatius, Athenagoras, Irenaeus, Clement of Alexandria) and West (Tertullian, Pope Dionysius); catalogs and rehabilitates, following Franzelin, four categories of vague or incautious Ante-Nicene expressions concerning the Son's relation to the Father; and candidly discusses the Ante-Nicene writers whose orthodoxy remains genuinely doubtful — the Didache, Hermas's Shepherd, Hippolytus, and Origen.

Surveys the Nicene and Post-Nicene defense of the Trinity — Alexander and Athanasius against Arius, then Athanasius, the Cappadocians, Amphilochius, and Didymus the Blind against Macedonius in the East, and Ambrose and Augustine in the West — then details the Fathers' polemical exegesis of the Arian proof-texts: Proverbs VIII, 22 ('The Lord created/possessed me'), John XIV, 28 ('The Father is greater than I'), and the Macedonian appeals to Romans VIII, 26 and 1 Corinthians VIII, 6. Closes Section 2 and Chapter II.

Opens Chapter III by defining 'Procession' as the origination of one Divine Person from another, and distinguishing the two Processions, Generation and Spiration. Section 1 then proves the Son's eternal generation from the Father, both from Scripture (Heb. I, 5; Ps. CIX, 3; John I, 18) and from Patristic and conciliar tradition (St. Hilary, St. Augustine, the Athanasian Creed, Pope Damasus's anathemas), and shows that the relation of Generation involves only the Father and the Son.

Opens Section 2 by distinguishing Spiration from Generation and stating the Filioque dogma against the Greek schismatics. Traces the historical origins of the denial of the Filioque through the Jerusalem monks of 808 and Photius's elevation of the dispute to a palmary dogma of the Greek Church, through the Great Schism to 1453, and the Church's progressive definition of the Holy Ghost's double procession from the Council of Toledo (589) through the Fourth Lateran Council (1215) and the Councils of Lyons (1274) and Florence (1439).

Begins the positive proof of the Filioque from Scripture: (a) the Holy Ghost is called 'the Spirit of the Son' as well as 'the Spirit of the Father'; (b) the Holy Ghost's 'Mission' by the Son as well as the Father implies His procession from both; and (c) the principal argument, from John XVI, 13–15, that the Holy Ghost 'receives' from Christ exactly as He 'receives' His essence from the Father, refuting the Greek schismatics' interpolated reading of the Greek text.

Completes Article 2 and Chapter III by marshaling the Greek Fathers' own testimony for the Filioque — Athanasius, Basil, Gregory of Nazianzus, Gregory of Nyssa, Epiphanius, Didymus the Blind, and Cyril of Alexandria — culminating in Cardinal Bessarion's Florence synthesis reconciling the Greek 'through the Son' and Latin 'and the Son' formulas. Closes with the theological argument from the Son's and Holy Ghost's hypostatic distinction, defended against Duns Scotus's objection.

Opens Chapter IV by explaining that the Trinity is an absolute mystery, indemonstrable by unaided reason even after Revelation. Surveys the legitimate, merely illustrative use of created analogies by the Fathers and Schoolmen — especially Augustine's psychological analogy of self-knowledge and self-love — as against the illegitimate rationalist 'demonstrations' of Raymond Lully, Anton Günther, and Rosmini (the latter two condemned by name), and shows how reason can refute infidel objections (Schopenhauer, Strauss, Harnack) without itself demonstrating the mystery.

Establishes, as a certain theological conclusion rather than a defined dogma, that the Son's Generation is an act of the divine intellect (shown by the titles 'Logos' and 'Image,' and by Augustine's psychological analogy) while the Holy Ghost's Spiration is an act of the divine will or love (shown by the titles 'Spirit,' 'Holy,' and 'Gift of God'). Then analyzes the essential difference between the two Processions using the Scholastic definition of generation and the intellect/will distinction, concluding that there can be only one Son and one Holy Ghost.

Closes Section 2 by examining two disputed speculative questions: whether the Logos is begotten from the Father's knowledge of Himself alone or also of creatures and merely possible beings (against the extremes of Scotus and Gregory of Valentia, favoring the Thomist middle position that possibles enter necessarily into the Word while actual creatures are uttered only concomitantly and per accidens), and the parallel question for the Holy Ghost's procession from notional Love, concluding that love for the merely possible also enters into the act of Spiration.

Opens Section 3 with a Scholastic definition, built up by successive differentiae, of Hypostasis (an individual, complete, self-contained substance — substantia prima, integra, tota in se) and Person (a rational Hypostasis). Refutes Locke's and Günther's consciousness-based theory of personality as destructive of both the Trinity and Christ's uni-personality, and traces the historical struggle to fix a common Greek, Latin, and Syriac terminology (ousia/hypostasis vs. substantia/persona), culminating in St. Athanasius's reconciling formula at the Council of Alexandria (362).

Completes Section 3 by establishing the Four Real Relations in God (active and passive Generation, active and passive Spiration), the fundamental law of the Trinity ('In Deo omnia sunt unum, ubi non obviat relationis oppositio'), and the doctrine of the three relationes personificae (Paternity, Filiation, Passive Spiration) that alone constitute Persons. Explains why active Spiration, though a real relation, does not produce a fourth Hypostasis, and shows how the Greek denial of the Filioque undermines this entire structure.

Distinguishes personal Properties (Paternity, Filiation, active and passive Spiration, and the Father's innascibility) from properties of persons, and reconciles the Persons' distinct relative perfections with their absolute coequality through their essential identity with the one Divine Nature and their mutual immanence (perichoresis). Then treats the Divine Notions — the marks by which one Person is known as distinct from another — arriving at the traditional five: innascibility, active and passive Generation, and active and passive Spiration. Closes with the neat summary: one Nature, two Processions, three Hypostases, four Relations, five Properties and Notions.

Closes Chapter IV and Part I of the treatise. Treats the Divine Appropriations — ascribing to one Person, for revelatory purposes and under a strict law of intrinsic fitness, an attribute or operation actually common to all Three (divine names, absolute attributes, outward operations of creation-redemption-sanctification, and worship) — and the Divine Missions, defined as the eternal Procession of a Person considered in relation to a temporal creatural effect. Distinguishes visible from invisible Missions, and Mission from the cognate notions of Indwelling and Apparition.

Opens Part II of the treatise (Unity in Trinity), which will show that the dogma of the Trinity neither destroys nor endangers the unity and simplicity of God. Chapter I, Section 1 treats Tritheism — the heresy of Philoponus, Abbot Joachim of Flora, and Anton Günther — and its condemnation, centering on the Fourth Lateran Council's detailed teaching on the 'summa res' that is at once absolute (the one Divine Nature) and relative (each of the three Persons), and the Thomist 'virtual distinction' commonly used to explain how Nature and Person differ without really dividing the Godhead.

Proves from Scripture and Tradition that the Three Divine Persons are consubstantial in the strict sense of numerical identity of nature (tautousia), not a merely generic or specific unity. The Scriptural argument centers on John X, 30 ('I and the Father are one') and its context; the Patristic argument answers Harnack's charge that the Nicene Fathers understood homoousios only generically, showing from Athanasius, the Council of Alexandria (362), Basil, Gregory Nazianzen, and Augustine that they meant strict identity of essence, and defends Gregory of Nyssa's seemingly weaker analogy from human unity.

Proves that the Three Divine Persons have but one external operation (operatio ad extra), grounding the doctrine in the conciliar definitions of the Lateran Synod of 649 and the Fourth Lateran and Florentine Councils, then in Scripture (John V, 17-19; XIV, 10; Augustine's exegesis of 'similiter'), in Patristic Tradition (Cyril of Alexandria, the formula 'Pater per Filium in Spiritu Sancto omnia operatur'), and theologically from the axiom 'operari sequitur esse' — condemning in advance Günther's Tritheistic notion that each Divine Person acts separately ad extra.

Closes the entire treatise with the doctrine of Perichoresis (circumincession) — the mutual interpenetration and inexistence of the Three Divine Persons, grounded primarily in their Consubstantiality and secondarily in the divine Processions and Relations. Distinguishes true Perichoresis from mere omnipresence (rejecting Suarez's and Ruiz's account), proves it from Scripture (John XIV, 11; X, 30) and the Eleventh Council of Toledo, and shows its dogmatic importance as the final synthesis of the treatise's two governing themes: Trinitas in Unitate and Unitas in Trinitate.