church; however, he forced other Christians to consider which texts were canonical and why. He spread his beliefs widely; they became known as Marcionism. In the introduction to his book Early Christian Writings, Henry Wace stated: quotes Tertullian's De praescriptione haereticorum 30: Note 61 of page 308 adds: Other scholars propose that it was Melito of Sardis who originally coined the phrase Old Testament, which is associated with Supersessionism. Robert M. Price argues that the evidence that the early church fathers, such as Clement, Ignatius, and Polycarp, knew of the Pauline epistles is unclear, and concludes that Marcion was the first person to collect Paul's writings to various churches and to treat ten Pauline letters, some of them Marcion's own compositions, together with an earlier version of Luke (not the Gospel of Luke as now known): Justin Martyr In the mid-2nd century, Justin Martyr (whose writings span the period from c. 145 to 163) mentions the "memoirs of the apostles", which Christians called "gospels" and which were regarded as on par with the Old Testament. Scholars are divided on whether there is any evidence that Justin included the Gospel of John among the "memoirs of the apostles", or whether, on the contrary, he based his doctrine of the Logos on it. Justin quotes the letters of Paul, 1 Peter, and Acts in his writings. In Justin's works, distinct references are found to Romans, 1 Corinthians, Galatians, Ephesians, Colossians, and 2 Thessalonians, and possible ones to Philippians, Titus, and 1 Timothy. In addition, he refers to an account from an unnamed source of the baptism of Jesus which differs from that provided by the synoptic gospels: Tatian Tatian was converted to Christianity by Justin Martyr on a visit to Rome around 150 and returned to Syria in 172 to reform the church there. Irenaeus Irenaeus of Lyon referred directly to a defined set of four gospels (the Tetramorph), c. 180. In his central work, Adversus Haereses Irenaeus denounced various early Christian groups that used only one gospel, such as Marcionism which used only Marcion's version of Luke, or the Ebionites which seem to have used an Aramaic version of Matthew, as well as groups that used more than four gospels, such as the Valentinians (A.H. 1.11). Based on the arguments Irenaeus made in support of only four authentic gospels, some interpreters deduce that the fourfold Gospel must have still been a