Irenaeus is the first patristic writer to make full use of the apostolic writings as Scripture.5 He knows and uses practically the full range of New Testament texts that we now recognize, and, for the Gospels, insists that there can be neither more nor less than four, or rather, one Gospel in four forms.6 In his great work, Against the Heresies, after describing the systems of the Gnostics in book 1, and demonstrating their inconsistencies in book 2, Irenaeus turns, in books 3 to 5, to “the demonstration