The Mysteries and the Hexameron

Ambrose’s mystagogical and exegetical works. De Mysteriis and De Sacramentis are the catecheses he gave to the newly baptized of Milan on the rites of Christian initiation — baptism, chrismation, and the Eucharist — and they are the prime witnesses to fourth-century Milanese liturgy and to a strong Latin eucharistic realism, in which the word of Christ changes the elements into His body and blood. The Hexameron is his Lenten homily-cycle on the six days of creation, modeled on Basil; around it stands a large body of allegorical commentary on the patriarchs, the Psalms, and the Gospel of Luke, drawing on Basil, Philo, and Origen. This file sets out the mystagogy and the exegesis.

Tradition: Pan-Orthodox (Church Father / Latin)

The Mystagogical Works

In the church of Ambrose’s Milan, adults were baptized at the Easter Vigil, and in the bright week that followed the bishop led the newly baptized through the meaning of the rites they had just received. Two works preserve this mystagogy — the explanation of the mysteria, the sacraments — and together they are the single richest source for the liturgy of Christian initiation in the fourth-century West:

De Mysteriis (“On the Mysteries”): a single polished book of nine chapters, the literary, revised form of the catechesis (Ambrose, De Mysteriis [CSEL 73, ed. Faller]; trans. NPNF II/10 and FOTC 44).
De Sacramentis (“On the Sacraments”): six books or sermons covering substantially the same ground in fuller and rougher form — apparently an actual stenographic transcript of Ambrose’s spoken Easter-week sermons, taken down by a listener and never revised (Ambrose, De Sacramentis [CSEL 73]; trans. FOTC 44).

[Disputed: the authenticity of De Sacramentis was long doubted — from the sixteenth century onward some assigned it to Maximus of Turin, and the NPNF editor (de Romestin, 1896) rejected Ambrosian authorship, which is why NPNF II/10 prints De Mysteriis but not De Sacramentis. The modern consensus, established by Otto Faller (the CSEL 73 editor) and R. H. Connolly and affirmed by Ramsey, accepts De Sacramentis as genuinely Ambrose’s — in Faller’s formula, “the author was Ambrose the speaker, not the writer”; Klaus Gamber was a late dissenter.] On this view the two works are the same teaching twice over — the rough preached version and the polished literary one.

Together they let us watch a Milanese Christian being made: the enrollment and Lenten preparation; the renunciation of Satan turning west and the profession turning east; the Effeta, the opening of the ears and nostrils in imitation of Christ healing the deaf man; the pre-baptismal anointing; the threefold immersion in the font with the threefold confession of Father, Son, and Spirit; the post-baptismal anointing and the “spiritual seal” (the chrismation); and the first Eucharist (Ambrose, De Mysteriis 1–8; De Sacramentis 1–4).

The Stages of the Rite

Set out in order, the Milanese initiation unfolds in a sequence that Ambrose explains stage by stage, and which Edward Yarnold reconstructs as the fullest Western parallel to the Eastern mystagogies of Cyril of Jerusalem and Theodore of Mopsuestia (Yarnold, The Awe-Inspiring Rites of Initiation, ch. on Ambrose). The candidates (competentes), having given in their names at the start of Lent, underwent scrutinies and exorcisms through the weeks of preparation, and on the threshold of baptism the rite of the Effeta (or Effatha) — the bishop touching ears and nostrils with the cry “Be opened,” in imitation of Christ at Mark 7:34 (Ambrose, De Sacramentis 1.1.2–3; De Mysteriis 1.3). In the baptistery proper the candidate first renounced the devil, his works, and his pomps, turned to the West (the region of darkness) to do so, and then turned East to profess allegiance to Christ (De Mysteriis 2.5–7; De Sacramentis 1.2.5–8). There followed the consecration of the font — the waters sanctified by the cross and the invocation, that the Spirit might descend upon them as upon the waters at the beginning (Genesis 1:2) and at the Jordan (De Mysteriis 3.8–4.21; De Sacramentis 1.5.15–2.7.23). The candidate then descended into the font for the threefold immersion, professing belief in Father, Son, and Holy Spirit at each plunge (De Sacramentis 2.7.20; De Mysteriis 5.28). Emerging, he was anointed — the post-baptismal chrismation that Ambrose calls the “spiritual seal” (signaculum spiritale), the gift of the sevenfold Spirit (De Mysteriis 7.42; De Sacramentis 3.2.8–10) — and, in a rite peculiar to Milan and discussed at length by Ambrose, the bishop washed the feet of the newly baptized in imitation of Christ at the Supper (John 13), a humility-rite Ambrose defends against the Roman practice of omitting it (De Sacramentis 3.1.4–7). Clothed in white, the neophytes then entered the church for the first time to receive the Eucharist (De Mysteriis 8.43; De Sacramentis 4–5).

Eucharistic Realism

The mystagogical works are also a major early Latin witness to a strong doctrine of the real change of the eucharistic elements — and to the conviction that it is effected by the words of Christ, the words of institution. Ambrose presses the point with a string of Old Testament miracles: if Moses’ rod could become a serpent, if the Nile could turn to blood, if iron could be made to float at Elisha’s word, then surely the word of Christ can change the nature of bread and wine. “If the word of Elijah had power even to bring down fire from heaven, shall not the word of Christ have power to change the nature of the elements?… He spoke and they were made” (Ambrose, De Mysteriis 9.52 [CSEL 73]; trans. NPNF II/10). And he caps the argument with the supreme precedent of the Virgin Birth: “Why do you seek the order of nature in the Body of Christ, seeing that the Lord Jesus Himself was born of a Virgin, not according to nature?” (De Mysteriis 9.53).

De Sacramentis states it even more bluntly, in the words that medieval Western eucharistic theology would build upon: “This bread is bread before the words of the sacraments; when consecration has been added, from bread it becomes the flesh of Christ… The word of Christ effects this sacrament (sermo Christi hoc conficit sacramentum)” (Ambrose, De Sacramentis 4.4.14 [CSEL 73]); and again, “Before it is consecrated it is bread; but where the words of Christ have been added, it is the body of Christ” (De Sacramentis 4.4.23). This Ambrosian language — the consecration effected by Christ’s own institutional words — became a foundation of later Latin sacramental theology and stands as a strong patristic witness to the reality of the eucharistic change, held in common with the East.

The Words of Institution and the Eastern Epiclesis

Ambrose’s stress on the words of Christ as the effective formula of the consecration invites comparison with the Eastern liturgical tradition, which characteristically locates the consecratory moment in the epiclesis — the invocation of the Holy Spirit upon the gifts, that He may “make this bread the precious Body of Christ.” The contrast is real but should not be read as a contradiction. Ambrose himself is not silent about the Spirit and the prayer of the Church: De Sacramentis preserves the earliest surviving form of the Roman canon, including a petition that God accept and bless the offering, and Ambrose’s account of the font (De Sacramentis 1.5.15ff.) everywhere presupposes that it is the Spirit who sanctifies (Yarnold, Awe-Inspiring Rites; Ramsey, Ambrose, 86–90). What Ambrose emphasizes, in the face of those who would reduce the sacrament to a bare sign, is that the change rests not on human power but on the divine word spoken in Christ’s own person — “the word of Christ effects this sacrament.” The Eastern tradition, emphasizing the same divine and not human agency, attributes the change to the operation of the Spirit invoked in the anaphora. The two are best understood as complementary patristic witnesses to a single conviction: that the elements are truly changed, and changed by God and not by men. The whole consecratory action — the recital of Christ’s words within the Spirit-invoking prayer of the Church — is one act, and the Latin and Greek fathers have between them named its two inseparable aspects, the dominical word and the Spirit’s descent. Ambrose’s testimony, far from standing against the East, supplies the Western half of a common patristic doctrine of the real change.

The Hexameron

Ambrose’s largest exegetical work is the Hexameron (Exameron), six books made up of nine homilies preached in a single week — probably Lent or Holy Week, around 386–387 — on the six days of creation in Genesis 1 (Ambrose, Hexameron [CSEL 32.1, ed. Schenkl]; trans. FOTC 42 and NPNF II/10). It is a free Latin adaptation of Basil of Caesarea’s Homilies on the Hexaemeron, the great Greek model, to which Ambrose adds material from Origen and from Latin natural-historical sources, ranging across the heavens, the seas, the plants, the beasts, and the birds, and reading the whole creation as a book pointing to its Maker and to moral lessons for the soul. [Disputed: the degree of dependence on Basil is debated — older scholarship saw near-translation, while recent work (e.g. A. H. Pierce) argues for a more selective, Origen-mediated reception rather than mere copying.] The Hexameron is, with De Spiritu Sancto (see De Spiritu Sancto), a leading example of Ambrose carrying the Greek fathers into Latin.

The work moves day by day through Genesis 1: the creation of the formless matter and the light (Book I); the firmament and the gathering of the waters (Book II); the dry land, the plants, and the seeds (Book III); the sun, moon, and stars (Book IV); the fishes and the birds (Book V); and the land animals and the creation of man in the image of God (Book VI), where Ambrose’s account of human dignity rises to its height (Ambrose, Hexameron 6.7.40–6.10.76; trans. FOTC 42). Its most characteristic feature is the constant turn from natural description to moral and spiritual lesson: the creatures are read as a vast book of exempla for the soul. The industry of the ant and the bee rebukes human sloth and teaches commonwealth; the halcyon brooding on the winter sea preaches God’s providence; the migratory birds shame the Christian who forgets the seasons of grace; the fish that keep within their appointed waters reprove the man who oversteps his bounds; the viper and the moray become an emblem of marriage (Ambrose, Hexameron 5.7.18–5.23.77; trans. FOTC 42; Ramsey, Ambrose, 78–80). This blend of natural theology — the order and beauty of creation as a testimony to the Creator — with the moralized natural history of the Physiologus tradition would feed directly into the medieval bestiary and the Western tradition of reading the “book of nature” alongside the book of Scripture.

The Exegetical Corpus

Around the Hexameron stands a large body of allegorical and moral commentary, the written residue of years of preaching, which made Ambrose the great popularizer of the spiritual, figurative reading of the Old Testament in the West — the very preaching that converted Augustine (see Preaching and Care). The Genesis and patriarch treatises lean heavily on Philo (whose allegories Ambrose Christianizes) and on Origen: De Paradiso, De Cain et Abel, De Noe, De Abraham, De Isaac vel anima, De Bono Mortis, De Iacob et vita beata, De Ioseph, De Patriarchis, De Fuga Saeculi, De Interpellatione Iob et David, De Apologia David, De Helia et ieiunio, De Nabuthae, and De Tobia (all in CSEL 32.1–2, ed. Schenkl; several in FOTC 42 and 65, trans. Savage and McHugh).

The treatise De Isaac vel anima and De Bono Mortis show Ambrose at his most mystical, reading the soul’s ascent to God through the Song of Songs in a manner that anticipates the Western contemplative tradition. In De Isaac vel anima — taking the marriage of Isaac and Rebecca as the type of the union of Christ and the soul — Ambrose draws on Origen’s lost commentary and homilies on the Song of Songs to trace the soul (anima) as the Bride who, wounded with love, seeks the Bridegroom, is drawn into His chambers, and ascends by stages from the things of sense to the contemplation of the Word (Ambrose, De Isaac vel anima 3.6–8.79 [CSEL 32.1]; trans. McHugh, FOTC 65). The companion piece, De Bono Mortis (“On the Good of Death”), turns the same mysticism toward the soul’s longing to be released from the body and gathered to God: death, for the soul in love with Christ, is not an evil but a passage and a gain, the consummation of the ascent begun in this life (Ambrose, De Bono Mortis 1.1–5.20 and 12.52–55 [CSEL 32.1]; trans. McHugh, FOTC 65). This nuptial and ascending reading of the Song — the soul as Bride, the staged ascent to contemplative union — Ambrose passed to the Latin West, where it would flower in Gregory the Great and, supremely, in Bernard of Clairvaux’s sermons on the Canticle. To these belong his great scriptural commentaries: the Expositio Evangelii secundum Lucam, ten books on Luke — his only complete surviving New Testament commentary, dependent on Origen — and the long expositions of the Psalms, the Expositio Psalmi 118 (on Psalm 118/119, CSEL 62) and the Explanatio Psalmorum XII (on twelve Psalms, CSEL 64). Across this corpus the method is constant: the literal sense honored but surpassed, every figure of the old covenant opened to Christ, the Church, and the moral life of the soul — the spiritual reading that was Ambrose’s most far-reaching gift to Latin Christianity.

References

Ambrose of Milan. De Mysteriis and De Sacramentis [CSEL 73, ed. Faller]; SC 25 bis (ed. Botte); De Mysteriis trans. NPNF II/10; both in FOTC 44 (trans. Deferrari). Loci: De Mysteriis 9.51–53; De Sacramentis 4.4.14, 4.4.23.
Ambrose of Milan. Hexameron [CSEL 32.1, ed. Schenkl]; trans. FOTC 42 (Savage) and NPNF II/10.
Ambrose of Milan. Exegetical works [CSEL 32.1–2, ed. Schenkl]; Expositio in Lucam [CSEL 32.4]; Expositio Psalmi 118 [CSEL 62]; Explanatio Psalmorum XII [CSEL 64, Petschenig]. Seven Exegetical Works trans. McHugh, FOTC 65.
Yarnold, Edward. The Awe-Inspiring Rites of Initiation: The Origins of the RCIA. 2nd ed. Edinburgh: T&T Clark, 1994. On the Milanese initiation rites in De Mysteriis / De Sacramentis.
Ramsey, Boniface. Ambrose. London: Routledge, 1997, 66–92. On the exegetical and mystagogical corpus; affirms the authenticity of De Sacramentis.
Faller, Otto. Introduction to CSEL 73. On the authorship of De Sacramentis.
Pierce, Alexander H. “Reconsidering Ambrose’s Reception of Basil’s Homiliae in Hexaemeron.” Zeitschrift für Antikes Christentum 23 (2019). On the degree of dependence on Basil.
Dudden, F. Homes. The Life and Times of St. Ambrose. 2 vols. Oxford: Clarendon Press, 1935, 2:450–500.