I forgot to mention that in my comments.
When were codexes invented? And it was not until Gutenberg's press that it became cheap enough for average persons to imagine have a copy.
http://en.wikipedia.org/wiki/Codex
WT comments
*** w07 8/15 p. 19 Do You Remember? ***
What role did the codex play in early Christianity?It appears that Christians used mainly the roll, or scroll, at least until the end of the first century C.E. Over the next century, there was a struggle between advocates of the codex and those of the scroll. Experts believe that the Christians’ use of the codex played a significant role in its widespread acceptance.—6/1, pages 14-15.
*** w99 8/15 p. 23 par. 19 Jehovah Prepares the Way ***Finally, consider how Jehovah has enabled his people to benefit from technological advances. Though early Christians did not live in an era of rapid technological advancement, one development they did make use of was the codex, or leaf-book. The codex replaced the cumbersome scroll. The book TheBirthoftheCodex states: “In contrast to the slow and piecemeal process by which the codex ousted the roll in secular literature, the Christian adoption of the codex seems to have been instant and universal.” This reference work also says: “So universal is the Christian use of the codex in the second century that its introduction must date well before A.D. 100.” The codex was easier to use than a scroll. Scriptures could be located faster. This surely helped the early Christians who, like Paul, not only explained the Scriptures but also ‘proved by references’ the things they were teaching.—Acts 17:2, 3.