The Diatessaron is the title given to the earliest extant harmony of the gospels. A harmony amalgamates the four canonical gospels either by placing them in columns side-by-side or by blending the four into a single account. While the original Diatessaron seems to have had a limited circulation, it was improved and translated into a number of languages by the end of the fourth century. It has survived in Greek, Syriac, Latin, Armenian, Ethiopic, Arabic, Persian, Middle Dutch, Old Saxon, Middle German, Middle Italian, and Middle English. While the original text was likely in Greek, the Syriac and Latin versions were the forms from which all later versions seem to be taken. They provide a continuous narrative of the four (or five) gospels by the blending or eliminating of parallel passages. In several early Christian centers, the Diatessaron became the primary gospel used in the church. In the 1920's a Greek fragment of the work was discovered at Dura Europos, in ex! treme eastern Syria, dating from the middle of the third century.
Since the Diatessaron has not survived in its original form, except for a single fragment, it needed to be reconstructed. This was one of the lifetime ambitions of Daniel Plooij, who published a number of articles of the Harmony. The sources he and others have used for this purpose are diverse texts that were derived from Greek, Syriac, or Latin archetypes. Later translations of the Diatessaron often rearranged the text, and several of them were "Vulgatized" to some degree. This means that the portions of the work that later differed from the canonical accounts embraced by the church were replaced by their more "authorized" form. This is the greatest difficulty in reconstructing the original text of the Diatessaron, since whatever readings that were unusual in the original text have been removed. The character of the later versions, nonetheless, enables scholars to classify them on the basis of provenance and language. Plooij demonstrates the Syriac origin of the Old-Latin Diatessaron in this scholarly essay.