Over at Unsettled Christianity, Joel Watts has a post about Justin Martyr and his references to the Gospels as “memoirs of the apostles,” in relation to Xenophon’s Memorabilia.
I’ve been working on this topic in my own research of late, and here’ what I’ve surmized.
Justin was acquainted with the Socratic tradition. He explicitly cites Plato and Xenophon, and he could well have known Xenophon’s Memoirs of Socrates and Plato’s “Socratic Dialogues” as they were highly esteemed among the philosophers that he debated with. Hardly unexpected given that many biographies were disseminated widely, not just in the Socratic tradition, but Pythagorean memoirs too, as circulated by the prominent historian Alexander Polyhistor in the middle of the first century in Rome. The philosopher Favorinus of Arelate (d. ca. 160), friend to Emperor Antoninus Pius, published his own “memoirs” around the same time that Justin was in Rome. By using the term apomnemoneumata, Justin is the first, as far as we can tell, to liken the Gospels to the biographical tradition. His attempt to approximate the Gospels to another known literary genre is without doubt our best clue to what type of literature that the Gospels were received as by their early readers. That is not to say that the Gospels are exactly modeled on any particular type of the biographical tradition, but the Gospels belonged to the same literary family. I suggest that Justin’s equating the Gospels with the biographical memoirs of great philosophers is an apologetic ploy, designed to show that Christianity was a genuine philosophy, and that Christian accounts of Jesus contained cultural sophistication, but without sophistry.
 Cf. Justin, 2 Apol. 10.5 (Plato’s Apology for Socrates); 10.8 (Socrates had some knowledge of Christ); 11.2-3 (Xenophon’s story of Herakles at the crossroads).
 Koester (Ancient Christian Gospels, 38-39) points out that the Latin designation for Xenophon’s biography of Socrates as Memorabilia,was not used until Johann Lenklau’s 1569 edition of Xenophon. Even so, the Greek title for the work, “First Book of Xenophon’s Memoirs of Socrates” was extant in some manuscripts and such a title, or a source like it, is probably what influenced Justin.
 David L. Dungan, A History of the Synoptic Problem: The Canon, the Text, the Composition, and the Interpretation of the Gospels (ABRL; New York: Doubleday, 1999), 31-32.
 Note the words of Martin Hengel (Acts and the History of Earliest Christianity [Philadelphia: Fortress, 1980], 29): “The ancient reader will probably have been well aware of the differences in style and education, say, between Mark and Xenophon; but he will also have noticed what the gospels had in common with the literature of biographical ‘reminiscences’ ‒ and unlike the majority of German New Testament scholars today, he did not mind at all regarding the evangelists as authors of biographical reminiscences of Jesus which went back to the disciples of Jesus themselves.”
 Justin calls Christianity “philosophy safe and simple” (Dial. Tryph. 8.1), he extols Christians as those “who have lived in accordance with the Divine Reason” (1 Apol. 46), and regards Jesus as a great philosophical teacher by drawing attention to the brevity rather than bombastic nature of Jesus’ teaching (Dial. Tryph. 18.1; 1 Apol. 14.4). See Stanton, Jesus and Gospel, 103-5; Dungan, History of the Synoptic Problem, 32.