Scripture & Tradition
The Biblical Canon and the Deuterocanonical Books
The Catholic Old Testament includes seven books—Tobit, Judith, Wisdom, Sirach, Baruch, and 1-2 Maccabees—that were part of the Greek Septuagint used by the apostles and were affirmed by early councils, before being removed by the Reformers in the 16th century.
Catholic teaching
The Church teaches that the canon of Scripture, the definitive list of inspired books, was itself settled by the Church's authority under the Holy Spirit's guidance, since Scripture nowhere provides its own table of contents. The Catholic canon of forty-six Old Testament books includes the deuterocanonical ('second canon,' meaning later confirmed, not lesser) books, which were part of the Septuagint, the Greek Old Testament that the apostles themselves habitually quoted, and which were used liturgically and cited as Scripture by early Christian writers well before any formal council addressed the question. Martin Luther, following the narrower Jewish rabbinic canon fixed after the time of Christ rather than the wider Christian usage of the Septuagint, removed these books from Protestant Bibles in the 1500s, terming them 'Apocrypha.'
Biblical foundation
The New Testament writers overwhelmingly quote the Old Testament from the Septuagint, the Greek translation that included the deuterocanonical books, showing these books circulated as Scripture in the milieu the apostles used. The Letter to the Hebrews alludes to events and language found in 2 Maccabees regarding the martyrs who were tortured, refusing to accept release, so that they might rise to a better life. Paul's teaching in Romans that all creation and even Gentile conscience reveal something of the Creator's wisdom closely echoes themes and even language found in the Wisdom of Solomon, suggesting Paul's familiarity with it as part of his Scriptural formation.
Scripture references
Historical evidence
The regional Councils of Hippo (393) and Carthage (397, 419), attended by St. Augustine, listed the same forty-six-book Old Testament canon Catholics use today, and this list was consistently reaffirmed in the Latin Church's usage for over a thousand years before the Reformation, including its use in St. Jerome's Vulgate, the standard Latin Bible from the late 4th century onward, even though Jerome himself initially expressed some hesitation about the deuterocanonical books' status relative to the Hebrew canon. The Council of Trent in 1546 formally and infallibly defined the canon in response to Luther's removal of these books, but was affirming longstanding practice rather than innovating; excavated Dead Sea Scrolls fragments of Tobit and Sirach in Hebrew and Aramaic further confirm these books' ancient Jewish origins and liturgical use before Christ.
The Church Fathers
“Tobias, Judith, Esther, two books of Esdras... two books of Maccabees... let this be made known also to our brother and fellow-priest Boniface.”
“The whole canon of the Scriptures... in which the books of these Maccabees are included, are held to be authoritative.”