The Fourth is clearly the latest of the Gospels, for it does not attempt fully to reproduce the facts presented in the other three, but assumes their existence. Its doctrines are also more fully developed, and its aim is not simply the giving of historical facts and teachings, but also, as it clearly states, that those reading it _might believe that Jesus was the Christ, the son of God, and that believing they might have life in his name_ (xx. 31). The motive that produced it was, therefore, apologetic and evangelical rather than merely historical. [Sidenote: _Review of growth of the Gospels_] A detailed comparison of the differences between the Gospels, as well as of their many points of likeness which often extend to exact verbal agreement, furnishes the data for reconstructing their history. In general the resulting conclusions are in perfect harmony with the testimony of the Church Fathers. Mark, the shortest and more distinctively narrative Gospel, is clearly the oldest of the four. Possibly it was originally intended to be the supplement of the other early source, Matthew's _Sayings of Jesus_, now known only through quotations. These two earliest known Christian records of the work of the Master in their original form were the chief sources quoted in the First and Third Gospels. So largely is Mark thus reproduced that, if lost, it would be possible from these to restore the book with the exception of only a few verses. But in addition, Matthew and Luke each have material peculiar to themselves, suggesting other independent written as well as oral sources. To such shorter written Gospels, and also to the oral testimony of eyewitnesses, Luke refers in his prologue. In the Fourth Gospel, the doctrinal motive already apparent in Matthew, and prominent in the Church at the beginning of the second Christian century, takes the precedence of the merely historical. A distinct source, the personal observation of the beloved disciple, probably also furnishes the majority of the illustrations which are here so effectively arrayed. [Sidenote: _Influences that produced the apocalypses_]