The tides by which traditions flow in different places are not simultaneous; they differ in time, in height, and in volume. No practice could be more mischievous than the habit of dating the relative spread of early beliefs simply by the dates of contemporary documents. Regard must be paid to local conditions.
In life as in nature there are variations of current and of coast formation. There are limits, of course, within which this caveat holds good; but, provided the interval of time is not too great, the view that St. Luke could begin to write in ignorance of a tradition already known elsewhere is not self-condemned. After all, St. Luke himself had access to much tradition which presumably was unknown to the First Evangelist (witness St. Luke's special matter).
Concerning the length of time we can allow the Virgin Birth tradition to have been already known elsewhere, when St. Luke began to write, there is room for difference of opinion. If, as we have contended, he became acquainted with it in the process of writing or immediately afterwards, the period can scarcely have been considerable. Perhaps it ought to be estimated in months rather than in years, but to say more would be idle speculation.
The farthest point therefore to which we can trace the existence of the Virgin Birth as a public tradition is some little time previous to the composition of the Third Gospel.
(3) It is a perfectly fair assumption to make that the public tradition must have had a private vogue before, and perhaps for some time before, it became public property. This view becomes especially probable in the light of what we have just seen, viz. that the spread of the public tradition among the primitive Christian communities covered an appreciable period of time. The question of the historical truth of the Virgin Birth is precisely the question of how far back the private tradition can be traced; whether it can go back to Mary the mother of Jesus, and whether satisfactory reasons can be given for a silence which extends beyond the period covered by the Pauline Epistles and the Second Gospel, and is broken only at last in the interval which shortly preceded the composition of the Gospels of Mt. and Lk. In this lies the real historical problem. Can the theory of a private authoritative tradition be vindicated? There are several questions which bear upon this problem. They are: (1) The question of the date of the First and of the Third Gospels; (2) The extent to which the credibility of the Gospels permits of the possibility of error; (3) The Alternative Theories of the origin of belief in the Virgin Birth; (4) The theological aspect of the tradition.
II. The Date of the Gospels in Relation to the Virgin Birth Tradition
The relation in which the question of the Date of the Gospels stands to the results reached is sufficiently clear. If we could fix the time when Mt. and Lk. were written, we could determine within comparatively narrow limits when the Virgin Birth tradition first gained currency. A conclusion upon this point would materially affect our estimate of the historical value of the tradition.
Until this stage we have deliberately refrained from assigning dates to the Gospels. The only things we have assumed are the priority of Mk. and the practically contemporaneous origin of Mt. and Lk. Our justification for this course lies in the great variety of opinion which exists on the question of date, and hence the desirability of keeping clear, as long as we can, from considerations which must vitally affect the results secured.
Unfortunately, as we have said, no sort of unanimity exists upon the question of the date of the Gospels. A glance at the extremely useful table which Dr. Moffatt prints on page 213 of his Introduction makes this clear. At first sight the position would appear chaotic, and we might well shrink from attempting to connect our results with specific dates. It is impossible, moreover, in a work like the present, to discuss the question in detail. Such a problem ought to be considered independently, and with regard to all the facts of the case. It would seem best therefore to ask what the consequences are, if we incline to any one of certain representative dates. We are at liberty, of course, to indicate our personal preferences, but, for the reasons stated, we shall have to agree to a measure of uncertainty. This is disappointing, but the responsibility must lie at the right door, and that door is the present failure of Biblical Scholarship to arrive at a consensus of opinion on the question of the date of the Gospels. Perfect agreement there will never be, but until there is substantial agreement every historical investigation into questions of New Testament origins must prove incomplete.