The relationship between the Coptic "Gospel of Thomas" and the synoptic gospels has been a matter of long-standing debate. Some maintain that the sayings of Jesus in Thomas reflect a line of transmission independent of the synoptic tradition; others contend that the Coptic collection is finally a reworking of the Greek synoptic gospels. This book proposes a third possibility: namely, that the "Gospel of Thomas" depends on a second-century Syriac gospel harmony, Tatian's "Diatessaron," written in 175 C.E. Following a linguistic analysis of Thomas, the author argues that the Coptic collection is actually a translation of a unified Syriac text which at places followed the wording and sequence of the "Diatessaron," The book argues for a late second-century C.E. dating of Thomas, rules out Thomas as a meaningful source for Historical Jesus research, and suggests possible links between Thomas and other mystical literature of the ancient near east. Paperback edition is available from the Society of Biblical Literature (www.sbl-site.org).