Jerome completed his translation of the Books of Solomon over a three day period during the summer of 398. He apologizes for not being able to fulfill the request of Bishops Cromatius and Heliodorus for commentaries on Hosea, Amos, Zechariah, and Malachi, and he blames this on a recent illness. Instead of the commentaries, he offers a translation of the three books of Solomon. He would finally complete his commentaries on the requested books in 406, which year marks the completion of Jerome’s commentaries on the Minor Prophets, and his turn toward the Major Prophets.
The following preface is especially interesting for the comments on the deuterocanonical books of Ecclesiasticus (a.k.a Ben Sira, a.k.a Sirach), and Wisdom of Solomon, which temper somewhat the remarks made earlier in Jerome’s preface to the Books of Kings. In that preface, he gave no indication that Jewish books outside the Jewish canon should be used by the church, but termed all these outside books “apocrypha”, thus anticipating modern Protestant use of the term. In this preface, he allows for continued use in the church of at least some of these “apocrypha”, and he explicitly names here Judith, Tobit, the books of Maccabees (presumably just the first and second books of Maccabees), Sirach, and Wisdom of Solomon. (The modern Catholic canon includes all six of these books as deuterocanonicals, along with Baruch and the longer forms of Esther and Daniel.)
Jerome’s view articulated here parallels that of his bosom-buddy Rufinus (Commentary on the Apostles’ Creed 36–37), and that of the great Alexandrian bishop Athanasius (in his famed 39th Festal Letter). Of course, these latter two Fathers did consider canonical the LXX text form of the OT books, whereas Jerome definitely favors the Hebrew text. This mediating view, though, contradicts that of Cyril of Jerusalem, who leaves no room for Christian use of the deuterocanonicals (in theory, though not in practice; Catechesis 4.33–36), and also that of Augustine of Hippo, who includes all the aforementioned books in his canon with equal authority (On Christian Doctrine 2.13).
Jerome to the bishops Cromatius and Heliodorus,
Let the epistle join those whom the priesthood joins; nay indeed, let not a page divide those whom the love of Christ binds together. You request commentaries on Hosea, Amos, Zechariah, and Malachi; I would have written them if I had been healthy. You send compensation for expenses, you sustain our stenographers and scribes, so that our ablest ingenuity may sweat for you. And behold from the side a crowded and diverse mob of requesters, as if either it would be fair for me to labor for others while you are hungry, or I would be liable to others more than you in the matter of giving and receiving. Therefore, though weakened by a long illness, lest I should be silent within this year and be mute among you, I have dedicated to your name a work of three days, viz. a translation of the three volumes of Solomon: Masloth, which the Hebrews call Parables, but the common edition calls Proverbs, Coeleth, which in Greek is Ecclesiastes, and in Latin we can say Speaker, and Sirassirim, which is rendered in our language as Song of Songs.
There is also the ever-virtuous book of Jesus son of Sirach, and another which is a pseudepigraph, inscribed Wisdom of Solomon. The first of these I have found also in Hebrew, not titled Ecclesiasticus as among the Latins, but Parables; to which were joined Ecclesiastes and Song of Songs, so that it equaled the resemblance of Solomon not only in the number of books, but also in the type of material. The second book is nowhere among the Hebrews, but even the very style smells of Greek eloquence; and several old writers affirm that it is from the Jew Philo. Therefore, just as the church reads Judith and Tobit and the books of the Maccabees, but does not receive them among the canonical scriptures, so also let it read these two volumes for the edification of the people, not for confirming the authority of ecclesiastical dogma.
If the edition of the seventy translators pleases anyone more, he has it from us previously emended; for we do not establish new things so that we might destroy the old. And also, when he reads most diligently, let him know that our things are better understood, which have not been corrupted by being poured into the third jar, but, having been entrusted to the purest jar straight from the wine-press, preserve their own flavor.
 Jean Gribemont, “The Translations: Jerome and Rufinus,” in A. DiBerardino (ed.), Patrology, vol. 4 (Italian, 1978; ET Westminster, MD: Christian Classics, 1986), 195–254 (225). This is a continuation of the Patrology begun by Johannes Quasten.
 See Gribemont, p. 234.
 It is doubtful whether Jerome was familiar with this terminology. He always called the Minor Prophets “The Twelve” or similar (e.g. see his prefaces to the Twelve Prophets and to the Books of Kings). In fact, most Christian writers thought of these prophets as a group under the designation Book of the Twelve (see the canon lists cited by H.B. Swete in his An Introduction to the Old Testament in Greek2 [Cambridge: University Press, 1914], 203–14, or available online here). The term “Minor Prophets” is not recorded for another few years, by Jerome’s contemporary Augustine (City of God 18.29, available here), though it appears that Augustine is citing common usage.
 Though see his Apology against Rufinus 2.33, where he does defend his use of the LXX additions to Daniel. This is probably just a matter of politics in his heated rivalry with Rufinus. On the whole question of Jerome’s attitude toward the Hebrew text, see Adam Kamesar, Jerome, Greek Scholarship, and the Hebrew Bible (Oxford: Clarendon, 1993).