It remains for us to speak of the documents which, presenting themselves as biographies of the Founder of Christianity, must naturally hold the first place in a _Life of Jesus_. A complete treatise upon the compilation of the Gospels would be a work of itself. Thanks to the excellent researches of which this question has been the object during thirty years, a problem which was formerly judged insurmountable has obtained a solution which, though it leaves room for many uncertainties, fully suffices for the necessities of history. We shall have occasion to return to this in our Second Book, the composition of the Gospels having been one of the most important facts for the future of Christianity in the second half of the first century. We will touch here only a single aspect of the subject, that which is indispensable to the completeness of our narrative. Leaving aside all which belongs to the portraiture of the apostolic times, we will inquire only in what degree the data furnished by the Gospels may be employed in a history formed according to rational principles.[1] [Footnote 1: Persons who wish to read more ample explanations, may consult, in addition to the work of M. Reville, previously cited, the writings of Reuss and Scherer in the _Revue de Theologie_, vol. x., xi., xv.; new series, ii., iii., iv.; and that of Nicolas in the _Revue Germanique_, Sept. and Dec., 1862; April and June, 1863.] That the Gospels are in part legendary, is evident, since they are full of miracles and of the supernatural; but legends have not all the same value. No one doubts the principal features of the life of Francis d'Assisi, although we meet the supernatural at every step. No one, on the other hand, accords credit to the _Life of Apollonius of Tyana_, because it was written long after the time of the hero, and purely as a romance. At what time, by what hands, under what circumstances, have the Gospels been compiled? This is the primary question upon which depends the opinion to be formed of their credibility. Each of the four Gospels bears at its head the name of a personage, known either in the apostolic history, or in the Gospel history itself. These four personages are not strictly given us as the authors. The formulae "according to Matthew," "according to Mark," "according to Luke," "according to John," do not imply that, in the most ancient opinion, these recitals were written from beginning to end by Matthew, Mark, Luke, and John,[1] they merely signify that these were the traditions proceeding from each of these apostles, and claiming their authority. It is clear that, if these titles are exact, the Gospels, without ceasing to be in part legendary, are of great value, since they enable us to go back to the half century which followed the death of Jesus, and in two instances, even to the eye-witnesses of his actions. [Footnote 1: In the same manner we say, "The Gospel according to the Hebrews," "The Gospel according to the Egyptians."]