the same textual characteristics has been empirically ascertained.
47. A third and specially important loss of homogeneousness occurs wherever the transmission of a writing has been much affected by what (§§ 5, 6) we have called mixture, the irregular combination into a single text of two or more texts belonging to different lines of transmission. Where books scattered in two or more copies are transcribed continuously into a single document (§ 46), the use of different exemplars is successive: here it is simultaneous. In this case the individuality, so to speak, of each mixed document is divided, and each element has its own characteristics; so that we need to know to which element of the document any given reading belongs, before we can tell what authority the reading derives from its attestation by the document. Such knowledge evidently cannot be furnished by the document itself; but, as we shall see presently, it may often be obtained through combinations of documents.
48. Lastly; the practical value of the simple application of Internal Evidence of Documents diminishes as they increase in number. It is of course in some sort available wherever a text is preserved in more than a single document, provided only that it is known in each variation which readings are supported by the several documents. Wherever it can be used at all, its use is indispensable at every turn; and where the documents are very few and not perceptibly connected, it is the best resource that criticism possesses. On the other hand, its direct utility varies with the simplicity of the documentary evidence; and it is only through the disturbing medium of arbitrary and untrustworthy rules that it can be made systematically available for writings preserved in a plurality
