Books for a Friend

Although Justin's letter of about 130 AD mentioned the memoirs and writings of the apostles, he did not say what exactly those were.  The next writer, however, was more detailed.  He was Melito, bishop of the church at Sardis about 170 AD.  He wrote a letter to Onesimus, a fellow Christian who had asked for an accurate statement of the ancient books.

Melito replied,

I accordingly proceeded to the East, and went to the very spot where the things in question were preached and took place; and, having made myself accurately acquainted with the books of the Old Testament, I have set them down below, and herewith send you the list. Their names are as follows:--

The five books of Moses--Genesis, Exodus, Leviticus, Numbers, Deuteronomy; Joshua, Judges, Ruth, the four books of Kings, the two of Chronicles, the book of the Psalms of David, the Proverbs of Solomon, also called the Book of Wisdom, Ecclesiastes, the Song of Songs, Job, the books of the prophets Isaiah, Jeremiah, of the twelve contained in a single book, Daniel, Ezekiel, Esdras.  (Eusebius, Church History, Book IV: 26)

Melito is the first Christian who left a written record of the accepted books of the Old Testament.  His list includes all the books of today but did not include the Apocrypha and did not include Esther (although there is some speculation that it could've been included in Esdras, which is otherwise Ezra and Nehemiah).

Although Melito did not explain why he did not include the Apocrypha, we can draw several other conclusions: first, by 170, there was not yet a widely-accepted canon of the Bible, not even of the Old Testament.  There was such a canon in the east, but Melito had to go there to discover it.  And second, there was apparently no consensus yet about the New Testament, or perhaps not yet even a sense that there ought to be a canon for the writings of the apostles, as Melito makes no mention of any books other than the Old Testament, although he does note that this list is the old testament: the first writer known to do so.  So third, he implied that there was a new testament, but apparently it had not yet been defined.

The Memoirs of the Apostles

Now that we know what codices are, we need to talk about how they came to be.  Or more specifically, how their contents came to be.  And that is mostly a story that can be followed over time, of a long slow development of writings read by Christians.

The first author of note is Justin Martyr.  He wrote a letter to the Roman emperor Antoninus Pius sometime between 155 and 157 AD (so about 130 years or so after the crucifixion of Jesus), explaining what these crazy Christians actually do: remember that most Romans knew the Christians only by rumor, or only that they refused to worship the emperor as a god.  Justin wrote his letter in an attempt to set the record straight.

And on the day called Sunday, all who live in cities or in the country gather together to one place, and the memoirs of the apostles or the writings of the prophets are read, as long as time permits; then, when the reader has ceased, the president verbally instructs, and exhorts to the imitation of these good things. Then we all rise together and pray, and, as we before said, when our prayer is ended, bread and wine and water are brought, and the president in like manner offers prayers and thanksgivings, according to his ability, and the people assent, saying Amen.

Emphasis mine; Justin does not tell the emperor exactly what is read, but several points can be made.  The "writings of the prophets" clearly refer to the Old Testament: the memoirs of the apostles sounds very much like the Gospels, or---less likely---some of their letters to churches.  And Justin writes as though this tradition of reading is wide-spread among the churches: if so, the memoirs were already widely available to the various churches by this date.