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their text ultimately from single lost documents, or from single lines of transmission consisting of successions of lost documents. The relation of the whole mass of documents containing a book to the single autograph is in fact repeated on a smaller scale by each subordinate set of documents for a large body of their readings ; and it is impossible to have any true conception of the origin of the present distribution of readings till it is clearly understood that fundamentally all textual transmission takes the form of a genea- logical tree, diverging into smaller and smaller branches, of which the extant documents are casual and scattered fragments or joints. This fundamental type of transmission is indeed greatly obscured in the New Testament by the coalescence of different branches of the tree through textual mixture, and the consequent rarity of pure representatives of the earlier and wholly divergent branches. But this seeming confusion is comparatively seldom productive of real and permanent difficulty in determining what lines of transmission did or did not contain a given reading in ancient times.
The use of genealogical evidence, like the use of 'internal evidence of documents', brings to the elucidation of each single place a knowledge gained by the examination of many, and thus involves three successive processes. In this instance they are, first, the analysis and comparison of the documentary evidence for a suc- cession of individual variations ; next, the investigation of the genealogical relations between the documents, and therefore be- tween their ancestors, by means of the materials thus obtained ; and thirdly, the application of these genealogical relations to the interpretation of the documentary evidence for each individual variation. The results of the interpretation of documentary evi- dence thus and thus alone made possible are various. In the first place, it winnows away a multitude of readings which genealogical relations prove to be of late origin, and which therefore cannot have been derived by transmission from the autograph. Further, as regards all other readings, it so presents and limits the possible genealogical antecedents of the existing combinations of docu- mentary evidence as to supply presumptions in favour of one read- ing against another, varying from what amounts under favourable circumstances to practically absolute certainty down to complete equipoise. On the other hand the inequalities and occasional am- biguities in the evidence for the genealogical relations frequently
