Complex sentence: A Gospel harmony is an attempt to merge or harmonize the canonical gospels of the Four Evangelists into a single gospel account, the earliest known example being the Diatesseron by Tatian in the 2nd century.
Split into simpler sentences: A Gospel harmony is an attempt to merge or harmonize the canonical gospels of the Four Evangelists into a single gospel narrative. The earliest known example is the Diatesseron by Tatian in the 2nd century.