Manuscripts, as the parents of printed books, have necessarily exercised the greatest influence on their development. A step which might have been very important was taken when, probably early in the fifth century, the form most convenient for the printed book was established by the definitive supersession of the roll form of manuscript by the _codex_, or manuscript in modern book form. Codices are of sufficient antiquity to be figured in the paintings at Pompeii, but the derivation from _caudices_, thin leaves of wood, shows that they were not at first much used for literary purposes, but rather for accounts or memoranda. When they began to compete with the roll, a step in the direction of convenience which may be appreciated by us if we can imagine that all our books had at one time been printed in newspaper form, we find the colophon already installed under the title of _index_. This did not denote the key to the contents of a book, thought so indispensable in modern times, but to the title, giving generally the subject and author of the book with the utmost brevity, and written at the end, precisely like a colophon, which in fact it was, though not bearing the name. As the papyrus roll was not bound, there could be no lettering upon a cover unless when, as was sometimes the case, a fine manuscript was inclosed within a case or wrappage for its protection; and the inconvenience of having to open every roll to find the title soon suggested the idea of hanging the index outside the roll on a separate slip, brightly dyed so as to attract attention. Examples may be seen in paintings from Pompeii. The general, though as yet by no means universal, displacement of papyrus by parchment led to the introduction of binding, early in the fifth century, as the best method of preserving codices. It had, of course, been practised before, but could not make much progress while the majority of books were papyrus scrolls; and even in the case of codices it seems to have been chiefly employed for the opportunity it afforded of adorning a valued manuscript with a splendid exterior. The disuse of the roll, however, soon made binding universal. In the Customs of the Augustinian priory at Barnwell it is distinctly laid down: “As the books ought to be mended, printed, and taken care of by the Librarian, so ought they to be properly bound by him.”