It seemed as if the solution of the problem was in sight when fragments of a Syriac palimpsest were discovered on Mount Sinai in February 1892 by Mrs. Lewis and her sister, Mrs. Gibson. These they perceived to be part of a very old manuscript of the Gospels, and Professor Bensly of Cambridge recognised that their text was closely related to that of the Curetonian. (_See Plate V._) A second expedition was made to Sinai in the spring of 1893, when the fragments were transcribed by Professor Bensly, F. C. Burkitt, and J. R. Harris. As Bensly died three days after their return, the manuscript was published by the others in 1894, with an introduction by Mrs. Lewis. On a third visit to Sinai this lady completed the work of the triumvirate, and also published an English translation of the whole. How, then, is this Sinai-Syriac or Lewis-Syriac, as it is called, related to the Curetonian and to the Peshitto? The problem becomes more complicated still by the introduction of a fourth factor, the most important of them all. [Sidenote: Tatian.] From early sources it was known that Tatian,[82] a Syrian and a pupil of Justin Martyr, composed a harmony of the Gospels called the =Diatessaron=—_i.e._ τὸ διὰ τεσσάρων εὐαγγέλιον, an expression which may be taken either as referring to the four Gospels or as a musical term equivalent to _harmony_ or _chord_. This Harmony was in use among the Syrians till the fifth century. Theodoret, Bishop of Cyrus, informs us that he destroyed 200 copies of it in his semi-Syriac, semi-Greek diocese.[83] About the same time Bishop Rabbulas of Edessa (407-435) instructed his presbyters and deacons to see that all the churches possessed and read a copy of the Distinct Gospel—_i.e._ not mixed or harmonised. The Lewis-Syriac bears this very title, _Gospel of the Distinct_ or _Divided_, which is found also as the title of Matthew’s Gospel in the Curetonian version. Tatian’s Harmony has not yet been discovered in Syriac, but a Latin Harmony of the Gospels derived from it has long been known, and in 1883 a Harmony in Arabic was published by Ciasca which proves to be a translation from the Syriac made by Ibn et-Tabib (d. 1043) or a recension of it. Again, in 1836 the Armenian version of a Syriac Commentary by Ephraem of Edessa (d. 373) was printed, and translated into Latin in 1876. [_Evangelii concordantis expositio facta a S. Ephraemo doctore Syro. In Latinum translata a J. B. Aucher, ed. G. Moesinger._ Venetiis.] Finally Theodor Zahn discovered in the works of the Syriac writer Aphraates, who wrote between 337 and 345, quotations which must be derived from this Harmony of Tatian; and isolated quotations from Tatian are also found in later Syriac authors. And so the materials are provided for deciding the question whether or not Tatian made use of an earlier Syriac version in the preparation of his Harmony, and how T^{(atian)}, Syr^{cu(reton)}, Syr^{sin} and Syr^{sch(aaf)}[84] are related to each other. The most probable view