I. Dogmatic and Controversial Works.
1. De Fide. The chief of these are the Five Books on the Faith, of which the two first were written in compliance with a request of the Emperor Gratian, a.d.378. Books III.-V. were written in 379 or 380, and seem to have been worked up from addresses delivered to the people [V. prol.9, 11; III.143; IV.119]. This treatise vindicates the Divinity of Christ from the attacks of the Arians, and has always enjoyed the highest reputation, being quoted and referred to again and again.
2. De Spiritu Sancto. The three books on the Holy Spirit may be considered as a continuation of the above treatise, and were also addressed to Gratian in compliance with his request, a.d.381. In this treatise St. Ambrose shows that the Holy Spirit is God, and of one nature and substance with the Father and the Son. He makes use of the Greek writers, SS. Didymus, Basil the Great, and Athanasius, and was on this ground attacked by St. Jerome. See Rufinus, Apol. adv. Hieron. II.23-25.
3. De Incarnationis Dominicæ Sacramento. The book on the Mystery of the Lord's Incarnation owed its origin to a challenge to dispute publicly given to St. Ambrose by two Arian chamberlains of Gratian. On the day appointed they were, as Paulinus relates in his life of St. Ambrose, thrown out of the chariot which was conveying them and killed. On the next day, that the people might not be disappointed, this discourse was delivered, but the reference made to the absence of the challengers hardly suits the story of Paulinus. The treatise is a very valuable argument in defence of our Lord's Divinity and Eternity, and that He is perfect God and perfect Man. In rewriting the address the Bishop added a refutation of the argument that the Begotten and the Unbegotten could not be of one nature and substance. The treatise may be considered as a supplement to that concerning the Faith.
4. De Mysteriis. A valuable treatise on the Mysteries, under which title St. Ambrose includes Baptism, with its complement, Confirmation, and the Eucharist. It is somewhat similar to the Catecheses Mystagogicæ of St. Cyril of Jerusalem, expounding the doctrine and ceremonies of these sacraments. On doctrinal grounds the authenticity of the work has been impugned by some modern writers, but there is no sufficient foundation for their arguments, as the teaching may be paralleled in many other passages of St. Ambrose. The date is not certain, but may be about a.d.387.
5. Libri duo de poenitentia. These books on Penitence were written about a.d.384, against the Novatians. In the first book the writer proves that the power of forgiving sins was left by Christ to His Church. In the second book, insisting on the necessity of repentance and confession, he also refutes the Novatian interpretations of Heb. vi.4-6 and St. Matt. xii.31-32. This treatise has also undeservedly been questioned on doctrinal grounds by some moderns.
These treatises are all translated in this volume.
II. Exegetical Works.
St. Ambrose was in the habit of explaining various books of holy Scripture in courses of lectures, which he subsequently worked up, often at the request of friends, into treatises in the shape in which they have come down to us. Of the class we have:
1. Hexaëmeron. This treatise, expounding the literal and moral sense of the work of the six days of creation [Gen. i.1-26], consists of nine addresses to the people of Milan, delivered in the last week of Lent, probably a.d.389, and is now divided into six books. The writer has studied Origen, but followed rather the teaching of St. Hippolytus and Basil the Great, though he expresses himself often quite in a different sense.
2. De Paradiso. This is the earliest or one of the earliest of the extant writings of St. Ambrose, though the exact date is uncertain. In it he discusses what and where Paradise was, and the question of the life of our first parents there, the temptation, fall and its results, and answers certain cavils of the Gnostics and Manichees. He also enters into an allegorical exposition comparing Paradise with the human soul.
3. De Cain et Abel. The treatise is now divided into two books, but the division is too inartistic to have been made by the writer. As to the date, it was later than the last treatise, but probably not many months. The interpretations are very mystical, and touch upon moral and dogmatic questions.
4. De Noe et Arca. This treatise has reached us in a mutilated condition. It was written probably before the De Officiis and De Abraham, but after the works on Paradise and Cain and Abel, though the exact date cannot be determined. The exposition is literal and allegorical.
5. De Patriarchis. Seven books preached and written at various dates about 387 or 388. The same kind of interpretation is followed in these as in the former treatises.
6. De fuga sæculi. Written probably about a.d.389-390. An instructive treatise setting forth the desirability of avoiding the dangers of the world, and for those who must live in the world, showing how to pass through them most safely.
7. De Elia et jejunio. A treatise composed from addresses delivered during Lent, certainly after a.d.386, possibly 389.
8. De Tobia. A work quoted by St. Augustine (C. Jul. Pelag. I.3, 10), consisting of sermons on the story of Tobias, and chiefly directed against the practice of usury.
9. De Nabuthe Jezraelita. One or two sermons against avarice, probably written about a.d.395.
10. Libri iv. de interpellatione Job et David. The first and third books have Job, the second and fourth David, for their subject, and formed a course of sermons the date of which is uncertain.
11. Apologia prophetæ David ad Theodosium Augustum. A number of addresses delivered, it would seem, about a.d.384, quoted also by St. Augustine.
12. Enarrationes in xii. Psalmos Davidicos. Commentaries on Psalms 1, 35-40, 43, 45, 47, 48, 61 (according to St. Ambrose's numbering). These seem to have been partly preached, partly dictated at various dates, and much in them is borrowed from St. Basil.
13. Expositio Psalmi cxviii. This treatise is one of the most carefully worked out of all the writings of St. Ambrose and consists of twenty-two addresses to the faithful, each address comprising one division of the Psalm. From various allusions, it would seem that the completed work dates from about a.d.388.
14. Expositio Evangelii secundum Lucam. The ten books of this commentary consist likewise of sermons in which St. Ambrose explained the Gospel during a period of one or two years, in 386 and 387.
III. Ethical Writings.
Among the ethical or moral writings of St. Ambrose, the first place is deservedly assigned to:
1. De Officiis Ministrorum. In three books, which are translated in this series.
2. De Virginibus. Three books concerning Virgins, addressed to his sister Marcellina in the year 377, probably, like most of the treatises of St. Ambrose, revised from addresses, the first of which was delivered on the festival of St. Agnes, January 21. This would seem to have been perhaps the very earliest of the writings of St. Ambrose, judging from the opening chapter. The treatise is referred to by St. Jerome, St. Augustine, Cassian, and others.
3. De Viduis. This shorter work, concerning Widows, was probably written not very long after the last mentioned treatise.
4. De Virginitate. A treatise on Virginity, the date of which cannot certainly be fixed, but the writing De Viduis is referred to in chapter 9.
5. De Institutione Virginis. A treatise on the training and discipline of a Virgin, addressed to Eusebius, either bishop or a noble of Bologna, after St. Ambrose had admitted his niece to the rank of Virgins, probably about a.d.391 or 392.
6. Exhortatio Virginitatis. A commendation of Virginity preached on the occasion of the consecration of a church at Florence by St. Ambrose, a.d.393 or 394.
IV. Sermons and Addresses.
1. Contra Auxentium. A sermon against Auxentius, concerning giving up the basilicas to the Arians, usually inserted between the twenty-first and twenty-second of the letters of St. Ambrose.
2. De Excessu fratris Satyri. The two addresses on the occasion of the death of St. Ambrose's brother Satyrus, translated in this volume.
3. De obitu Valentiniani Consolatio. The Emperor Valentinian having been murdered by Arbogastes, Count of Vienne, his body was brought to Milan, and remained two months unburied. At last Theodosius sent the necessary rescript, and at the funeral solemnities St. Ambrose delivered the address entitled the "Consolation."
4. De obitu Theodosii oratio. A discourse delivered forty days after the death of the Emperor Theodosius before the Emperor Honorius at Milan.
V. The Letters of St. Ambrose.
The Benedictine Editors of St. Ambrose have divided his Epistles into two classes: the first comprising those to which they thought it possible to assign dates; the second those which afford no data for a conclusion. Probably in many cases the exact year is not so certain as the editors have made it appear, but they seem arranged in a fairly probable consecutive order.
1. To the Emperor Gratian, in reply to his request for a treatise on the Faith. Written a.d.379, before August, as Gratian came to Milan in that month.
2. To Constantius, a bishop, on episcopal duties, and commending to him the care of the vacant see of Forum Cornelii, or Imola. Probably written about a.d.379.
3, 4. To Cornelius, Bishop of Comum, the first a friendly letter, the second containing also an invitation to the consecration of a church by Bassianus, Bishop of Laus Pompeia, now Lodi Vecchio, near Milan. Written probably after a.d.381.
5, 6. To Syagrius, Bishop of Verona. On a charge falsely brought against the Virgin Indicia. They may have been written a.d.380.
7, 8. To Justus, perhaps Bishop of Lyons. On holy Scripture. If the conjecture that Justus was the Bishop of Lyons is correct, written about 380 or 381.
9-12. Letters concerning the Council of Aquileia, held a.d.381, to the bishops of the provinces of Gaul, to the Emperor Gratian and his colleagues. Two men, Palladius and Secundianus, held Arian opinions, and the former appears to have asked Gratian to convoke a General Council, pleading that he was unjustly condemned. St. Ambrose pointed out to the Emperor that such a question as the orthodoxy of two persons could be settled by a local council in Italy; and as a result, by the Emperor's mandate, a council of Italian bishops met at Aquileia, other bishops having also permission to attend. Palladius and Secundianus were condemned, and these letters have reference to the proceedings at the council. They were probably written by St. Ambrose in the name of the council, a.d.381.
13, 14. Two letters addressed to Theodosius, the former relating the decisions of a council, probably held at Milan, on the Meletian schism at Antioch, and the latter further expressing the desire of the bishops for a council on this subject, and also on the opinions of Apollinaris. Written a.d.381 or 382.
15. To the Bishops of Macedonia, in reply to their notification of the death of Acholius, Bishop of Thessalonica, who baptized Theodosius, and had met St. Ambrose at a council in Rome. Written a.d.383.
16. To Anicius, on his election to succeed Acholius, whose labours and life are commended by St. Ambrose. Written a.d.383.
17, 18. On the occasion of the attempt of Symmachus and the heathen senators to procure the restitution of the image and Altar of Victory in the Roman Senate-house, frustrated by St. Ambrose, a.d.384.
19. To Vigilius, Bishop of Trent, subsequently martyred, written probably about a.d.385.
20. To his sister, Marcellina, giving an account of the frustrated attempts of the Arian and imperial party to gain possession of a basilica at Milan, a.d.385,
21. To the Emperor Valentinian II., declining the challenge to dispute with the Arian Auxentius before lay judges. a.d.386.
22. To his sister Marcellina, giving an account of the finding of the bodies of SS. Gervasius and Protasius, and of the consequent miracles. Written a.d.386.
23. To the bishops of the province of Æmilia, on the proper date for the observance of Easter, in 387. Written a.d.386.
24. To Valentinian II., with an account of St. Ambrose's second mission to Maximus on his behalf. Written probably a.d.387.
25, 26. Inscribed the former to Studius, the second to Irenæus, but from internal evidence these appear to be the same person. It deals with the question, how far a judge being a Christian may lawfully sentence any one to death. Written probably about a.d.388.
27-33. Addressed to Irenæus, on various questions. Written about a.d.387.
34-36. To Orontianus, a cleric, on the soul and other questions. Written after 386.
37, 38. To Simplicianus, who became the successor of St. Ambrose in the see of Milan, setting forth that holiness is perfect freedom.
39. To Faustinus, on the occasion of the death of a sister. Written probably after a.d.387.
40. To Theodosius. The Jewish synagogue at Callinicum in Mesopotamia having been destroyed by the Christians, and a meeting-house of the Valentinian heretics also burnt by the Catholics, Theodosius ordered that the bishop should rebuild the synagogue at his own expense, and the monks be punished. St. Ambrose remonstrates with the Emperor, and it would seem, from the following letter to his sister, at first unsuccessfully.
41. To his sister Marcellina, relating the circumstances alluded to above, and telling her of his sermon before the Emperor, and of his subsequent refusal to celebrate the Eucharist, until the Emperor had promised to rescind the order. The date of the two letters is a.d.388.
42. Reply of St. Ambrose and a synod at Milan to the notification of Pope Siricius announcing the sentence of excommunication passed upon Jovinian and his followers.
43, 44. To Horontianus, in reply to his inquiries on some points connected with the Creation.
45. To Sabinus, Bishop of Placentia, in answer to questions concerning Paradise.
46. To the same, on the subject of an Apollinarian heretic.
47-49. To the same, with books and on private matters.
50. To Chromatius, probably Bishop of Aquileia, explaining how evil men may be used to utter true prophecies.
51. To Theodosius, after the massacre at Thessalonica. Written a.d.390.
52. A private letter to Titianus.
53. To Theodosius, to express the sorrow of St. Ambrose at the death of Valentinian II., slain by Arbogastes.
54, 55. To Eusebius, not, it would seem, the Bishop of Bologna who was present at the Council of Aquileia, but rather a lay friend to whom St. Ambrose wrote his treatise on the training of a virgin. Probably written a.d.392 or 393.
56. To Theophilus. The troubles of the church of Antioch through the Meletian schism might have terminated on the death of Paulinus, had he not on his deathbed consecrated Evagrius as his successor in violation of the canons. Theodosius, being pressed by the Western bishops, now summoned a council at Capua, commanding Flavian to attend, which command he however disobeyed. The council referred the matter to Theophilus of Alexandria and the bishops of Egypt. But Flavian, as Theophilus had informed St. Ambrose, refused to submit to their decision. This is the reply of St. Ambrose advising Theophilus to summon Flavian once more, and communicate the result to Pope Siricius. The letter must have been written quite at the end of a.d.391, or the beginning of 392.
57. To Eugenius the usurper, to avoid whom St. Ambrose had left Milan, and to whose letters he had sent no reply. Written a.d.393.
58. To Sabinus, Bishop, on the resolution of Paulinus and Therasia to forsake the world. Written probably a.d.393.
59. To Severus, Bishop probably of Naples, telling him of James, a Persian priest, who had resolved to retire from the world into Campania, and contrasting this with his own troubles, owing to the invasion of Eugenius, a.d.393 or 394.
60. To Paternus, against a proposed incestuous marriage.
61. To Theodosius, after his victory over Eugenius. Written a.d.394.
62. To the same, urging him to be merciful to the followers of Eugenius. Written in the same year.
63. To the Church at Vercellæ.
The second division of the letters, being those which cannot be dated, begins here in the Benediction Edition.
64. To Irenæus, on the Manna.
65. To Simplicianus, on Exodus xxiv.6.
66. To Romulus, on Aaron's making the calf of the golden earrings.
67. To Simplicianus, showing how Moses yielded to Aaron in matters relating to his priestly character.
68. To Romulus. Explanation of the text Deut. xxviii.23.
69. To Irenæus, answering a question as to the prohibition under severe penalties in the Mosaic law, of disguising the sex by dress.
70, 71. To Horontianus, on part of the prophecy of Micah.
72. To Constantius, on the rite of circumcision.
73-76. To Irenæus. Why the law was given, and the scope of the Epistle to the Ephesians. The letter numbered 75 is plainly a continuation of 74, although inscribed to Clementianus, a difficulty similar to that about letter 26.
77, 78. To Horontianus, contrasting the condition of the Jew and the Christian.
79, 80. To Bellicius, on recovery from sickness, and on the miracle of healing the man blind from his birth.
81. To certain clergy, against despondency.
82. To Marcellus, concerning a lawsuit.
83. To Sisinnius, commending him for forgiving his son, who had married without consulting him.
84. To Cynegius.
85, 86. To Siricius, with thanks for letters, and commending Priscus.
87. To Segatius [more probably Phæbadius], Bishop of Agens, and Delphinus, Bishop of Bordeaux. Polybius, mentioned in the letter, was proconsul of Africa between the years 380 and 390.
88. To Atticus. Commendation of Priscus.
89. To Alypius. Acknowledgment of letters.
90. To Antonius. On the mutual affection of himself and St. Ambrose.
91. To Candidianus, probably a fellow-bishop. A letter of affection.
During the persecutions stirred up by the Arian Empress Justina, a.d.385-6, referred to in his 20th letter, St. Ambrose and the faithful spent the whole night in the basilica, and the holy Bishop employed the people in singing psalms and hymns. A large number of hymns have been attributed to St. Ambrose, the number having by some editors been brought down to twelve, of which, however, only four are certainly his compositions.
1. Eterne rerum Conditor, referred to by St. Augustine, Retract. I.21, and by St. Ambrose himself, Hexaëm. V.24, 88. The hymn is still in use at Lauds on Sunday.
2. Deus Creator omnium. Quoted by St. Augustine, Conf. IX.12, 32.
3. Jam surigit hora tertia. Also quoted by St. Augustine.
4. Veni Redemptor gentium. A Christmas hymn, quoted by Pope Celestine, a.d.430, in a sermon against the Nestorians, preached before a synod at Rome, and also by other writers.
Of other hymns one commencing, Illuminans Altissimus, is quoted by Cassiodorus as an Epiphany hymn by St. Ambrose, and the same author refers to another, Orabo mente Dominum. The Benedictine Editors admit six other hymns, but they are supported by no authority anterior to Venerable Bede.
VII. Doubtful and Spurious Works.
This volume cannot of course comprehend the arguments and discussions necessary for any critical examination of certain works whether doubtful or certainly spurious, but their names may be given and certain conclusions stated.
1. Five books on the Jewish war, ordinarily attributed to Hegisippus. This is a translation into Latin and a condensation in part of the well-known work of Josephus. Ihm, a very thorough student of St. Ambrose, seems quite disposed to maintain after careful examination that this is the work of St. Ambrose.
2. De lege Dei. This treatise, a sort of compendium of Roman law in the fourth century, and comparison of it with the law of Moses, is ascribed, in a translation published by Mai,  to St. Ambrose, who is said to have undertaken the work at the command of Theodosius. On the authenticity, however, of this treatise there probably will always remain much doubt.
3. Among works more or less doubtful are De Sacramentis, admitted by the Benedictines, but rejected, and apparently on sufficient grounds, by Ihm.
4. Apologia David altera. Suspected by Erasmus, Tillemont, and Ihm.
5. De lapsu Virginis consecratæ. A severe castigation of a fallen virgin and of her seducer. The treatise seems to have been written by a certain Bishop of Nicetas, and a ms. at speaks of it as having been revised by St. Ambrose.
6. There are further three brief addresses ascribed by some persons to St. Ambrose, touching on the question of selling all and giving to the poor. Some of the matter is like St. Ambrose, but the same cannot be said of the diction and style.
VIII. Lost Writings of St. Ambrose.
1. Expositio Isaiæ prophetiæ, referred to by St. Augustine as well as by St. Ambrose himself.
2. Liber de Sacramento regenerationis sive de philosophia, referred to by St. Augustine.
3. Libellus ad Pansophium puerum, written a.d.393-4, according to Paulinus in his life of St. Ambrose.
4. Libri quatuor regnorum, referred to in the introduction to the work on the Jewish war.
5. Expositio fidei, quoted by Theodoret and others as a writing of St. Ambrose.
 Scriptorum veterum nova Collectio, Vol. X.