Why they are so called.
Why they are so called.
§ 64. Canonical books are so called from 
[“rule”], a little word that is taken from Ps. 19:[14]; 2 Cor. 10:13; Gal. 6:16; Phil. 3:16. Although the apostle is speaking there not about the universal norm of faith but about that main point of heavenly instruction—that one must by no means confuse the righteousness of the Law with that of the Gospel or of faith—nevertheless he calls the instruction 
because he is claiming that the things the false prophets were teaching had to be examined according to the certain and indubitable rule, and if anywhere they were not in harmony with it, those things would have to be rejected. Elsewhere the writers of the Church call them 
[“written”], 
[“undoubtedly written”], 
[“notarized”], and testamentarii [“testamentary”] books because, as all agree, they pertain without ambiguity to the divine testament. (See Nicephorus, Hist. eccles., bk. 1, c. 1.) They are called the books “received” by Epiphanius (De mens. et ponderib., p. 567). They are called “legitimate, approved by the consensus and witness of all, true and genuine” by Eusebius (Hist., bk. 3, c. 9), Augustine (Contra adversar. legis et prophetar., bk. 2, c. 1), and Nazianzen (Carm. de script. sacr., p. 952). They are called “catholic” because they embrace the immovable foundation of the catholic faith and “ecclesiastical” because they have earned the approval of all the churches (Augustine, Contra Faustum, bk. 23, c. 9). They are called 
[“specified books”] because Christ Himself declared that they are in the canon (Epiphanius, Haeres. 8).
On the other hand, the apocryphal books are called this from 
, which is to say “hidden,” because “their secret origin has not been clarified by those whose testimony has caused the authority of the true Scriptures to come to us.” (This explanation of the term is given by Augustine, Contra Faustum, bk. 9, c. 2.) In his prologue on the Proverbs of Solomon, Jerome gives as the explanation that “they are not read publicly in the Church to prove the authority of the dogmas of the Church but only to edify behavior.”
** There are those who think they are called apocryphal “because they are ‘not in the holy crypt’ and library of books divinely given to the Church.” Epiphanius, De pond., bk. 2, calls this Aron, that is, the ark or repository of the Church in which the divine books used to be put away. Or [they are so called] because they are 
, “worthy to be hidden rather than read,” as Athanasius thinks (Synopsi., vol. 2, p. 134). **
A gloss on [the Jus canonicum,] dist. 15, c. Sancta Romana, says that those are called apocryphal books “whose author is unknown.” By this definition, however, many books of the Old Testament that are surely canonical, such as Ruth, Kings, and Chronicles, etc., would be apocryphal.