cording to the number and genealogical relations of the whole body of extant documents. If a text is preserved in but two documents, every reading of each where they differ is a singular reading, one or other of which must be right; unless indeed both are wrong, and the true reading has perished. If the documents are more numerous, the singular readings of one document have no less prima facie authority than the rival readings found in all other documents alike, provided that the other documents have had a common original (see § 52), making the readings common to them to be virtually, though not in appearance, as 'singular' as the others. The same principle holds good whatever be the total number of documents, unless they have all only one common ancestor; that is, the prima facie authority of the singular readings of any document cannot be estimated by the bare numerical relation (see §§ 54—57), but varies partly with the independence of ancestry of the one document in relation to all the rest, partly with the affinities of ancestry among the rest. Where the whole pedigree is very complex, as in the New Testament, any documents which frequently stand in very small groups attesting evidently genuine readings, against the bulk of documents of various ages, must evidently contain so large elements having an independent ancestry that the a priori presumption against their singular readings cannot be much greater than against singular readings at their best, that is, in texts preserved in two documents only.
310. On the other hand (see §§ 56, 58) the singular readings of a document may always be due either to inheritance from a more or less remote ancestry, which may be of any degree of purity, or to quite recent
