The Diatessaron (c 150 - 160) is the most prominent Gospel harmony created by Tatian, an early Christian apologist and ascetic. The term "diatessaron" is from Middle English ("interval of a fourth") by way of Latin, diatessaron ("made of four [ingredients]"), and ultimately Greek, diatessaron ("out of four"; i.e., dia, "according to" and tessaron [genitive of tessares], "four"). Tatian combined the four gospels - Matthew, Mark, Luke, and John - into a single narrative.
Tatian of Adiabene, or Tatian the Syrian or Tatian the Assyrian, (Latin: Tatianus; Ancient Greek: Τατιανός ο Σύρος; Classical Syriac: ܛܛܝܢܘܣ; c. 120 – c. 180 AD) was an Assyrian Christian writer and theologian of the 2nd century. Tatian's most influential work is the Diatessaron, a Biblical paraphrase, or "harmony", of the four gospels that became the standard text of the four gospels in the Syriac-speaking churches until the 5th-century, after which it gave way to the four separate gospels in the Peshitta version.