Here is Harnack's attempt to determine exactly the second source of Matthew and Luke (Q) both in regard to its extent and its contents, and to estimate its value both in itself and relative to the Gospel of Mark. Harnack begins with stylistic analysis of the non-Marcan texts that Matthew and Luke have in common, and concludes that Matthew more faithfully represents Q. He then proceeds to attempt to demonstrate that Q has a distinctive vocabulary and style.