The discovery of papyrus copies of the Gospels of Luke and John dating from c. 200 C.E. or a bit earlier that preserve a text very similar to the text of Sinaiticus and Vaticanus demonstrates that these two fourth-century manuscripts in fact preserve a textual tradition that dates back at least to around the time of Irenaeus. These papyri, known as P66 and P75, are both in the Bodmer collection in Geneva.