These [New Testament papyrus] fragments are also of interest in showing us the form in which the Scriptures circulated in those early centuries of the Church, before the advent of the great official vellum codices of the fourth century. Many of them represent the ‘poor men’s Bibles’, Bible intended for private, rather than for church use. They show us also that not all of the later Bibles were of the handsome type of the Codex Sinaiticus and Vaticanus, but that the Scriptures were within the reach of the more modest purses of the great mass of Christians. Most of the modest Bibles have perished, the more sumptuous alone surviving, yet they have not disappeared without leaving at least these meagre traces of their one time widespread existence. The Word could be known and cherished by the poor man as well as by the rich, for to such the Lord came with a message of good news.

Ellwood M. Schofield, The Papyrus Fragments of the Greek New Testament (diss., SBTS, Louisville, 1936), 336-337.

It is commonly asserted (e.g. Kenyon’s Palaeography of Greek Papyri, p. 24) that the book form is characteristic of the close of the papyrus period, and that the use of papyrus in codices was an experiment which was soon given up in favor of the more durable vellum. But the evidence now available does not justify either of these generalizations. When the papyrus book first made its appearance in Egypt it is impossible to say; but at any rate it was in common use for theological literature in the third century. Indeed the theological fragments which can be placed in that century are almost without exception derived from papyrus codices [= book form], not from rolls [= scroll form]. This fact can scarcely be due to accident; and it points to a prevalence of the book form at that early date much greater than is frequently supposed. Moreover, papyrus in the book form did not run so insignificant source. It may fairly claim to have made a good fight, if not to have held its own, in Egypt against vellum so long as Greek MSS. continued to be written there.

Bernard Pyne Grenfell and Arthur Surridge Hunt, The Oxyrhynchus Papyri II (London: 1899), 2-3.