Erasures, additions, corrections, substitutions — Sinaiticus reveals a Bible-in-process. Between the 4th and 12th centuries, various scribes changed earlier colleagues' bad spelling. Of more theological significance, the Gospel of Mark ends early. Sinaiticus even contains two books that didn't make the later canon cut, the Epistle of Apostle Barnabas and the Shepherd of Hermas. The changes are significant, according to British Library curator Scot McKendrick, because "the recognition is that Scripture, as it comes down to us, is transmitted by human hand."