Tatian is a witness whose evidence our author next tries to set aside. He was an Assyrian by birth, a disciple of Justin Martyr at Rome, and afterwards, having joined the sect of the Eucratites, a conspicuous exponent of their austere and ascetic doctrines. The only one of his writings extant is his Oration to the Greeks, written after Justin's death, as it refers to that event, and it is generally dated A.D. 170-175. One point contested is Canon Westcott's affirmation that it contains a "clear reference" to a parable recorded by Matthew:[44] "The kingdom of heaven is like unto treasure hidden in a field, which a man found and hid, and for his joy he goeth and selleth all that he hath and buyeth that field." And the supposed reference by Tatian is, "For by means of a certain hidden treasure he has taken to himself all that we possess, for which, while we are digging, we are indeed covered with dust, but we succeed in making it our fixed possession."[45] [44] Matt. xiii. 44. [45] "Orat. ad Gr." § 30. There is certainly not much similarity between the two passages, although Tatian may be well supposed to have had the parable in his mind when he wrote. The more important question is, Did Tatian write "A Harmony of Four Gospels," which recognises our four Evangelists? Was his Diatessaron such a book, or was it the Gospel according to the Hebrews? If the latter, what is the Gospel according to the Hebrews? I say it is probable it is the corrupted Hebrew translation of the Greek Gospel of Matthew, and this conjecture has more in its favour than our author's hypothesis.