40. The first effectual security against the uncertainties of Internal Evidence of Readings is found in what may be termed Internal Evidence of Documents, that is, the general characteristics of the texts contained in them as learned directly from themselves by continuous study of the whole or considerable parts. This and this alone supplies entirely trustworthy knowledge as to the relative value of different documents. If we compare successively the readings of two documents in all their variations, we have ample materials for ascertaining the leading merits and defects of each. Readings authenticated by the coincidence of strong Intrinsic and strong Transcriptional Probability, or it may be by one alone of these Probabilities in exceptional strength and clearness and uncontradicted by the other, are almost always to be found sufficiently numerous to supply a solid basis for inference. Moreover they can safely be supplemented by provisional judgements on similar evidence in the more numerous variations where a critic cannot but form a strong impression as to the probabilities of reading, though he dare not trust it absolutely. Where then one of the documents is found habitually to contain these morally certain or at least strongly preferred readings, and the other habitually to contain their rejected rivals, we can have no doubt, first, that the text of the first has been transmitted in comparative purity, and that the text of the second has suffered comparatively large corruption; and next, that the superiority of the first must be as great in the variations in which Internal Evidence of Readings has furnished no decisive criterion as in those which have enabled us to form a comparative appreciation of the two texts. By this cautious advance from the known to the unknown we are enabled to deal confidently with a
