codex not a roll whereas for non-Christian papyri the roll dominated until the fourth century. The papyrus fragment containing Hebrews known as Papyrus 13 (see Plate 1) is written on the back of a reused roll. This is a well-established method of saving writing material: an old parchment roll, no longer required, was used on the outside. It is known as an opisthograph (i.e. written on the back). In the case of a codex, recycling also occurred. An old manuscript could be scraped clean and used over