Moreover, there is a progression in language itself, independent of any alterations in the objects represented by words. Whenever a vocabulary affords a choice of appellatives, even for immutable objects or notions, the caprices of conversation or of literature--affectation perhaps, or excessive refinement, will, from time to time, occasion a new selection to be made. In all those terms, especially, which either bring with them ideas too familiar to accord with the proprieties of an elevated style, or which are in any degree offensive to delicacy, there will take place a continual, and, sometimes, even a rapid, substitution of new for old phrases--not because the new are in themselves more dignified, or more pure than the old; but because, when first introduced, they are untainted by gross associations or vulgar use. Every language, therefore, copious specimens of which are extant, and of which the progress is known, contains a latent history of the people through whose lips it has passed, and furnishes to the scholar a series of recondite dates, by means of which literary remains may almost with certainty be assigned to their proper age. This sort of evidence bears the same relation to the history of _books_, which that derived from the successive changes known to have taken place in the mode of writing bears to the history of _manuscripts_. It is of a subsidiary kind, and from its very indirectness it often deserves peculiar attention. We have now seen on what grounds it is, generally, that with reasonable confidence the extant works of ancient authors may be accepted as being such in truth. In presenting this statement of the case, nothing more has been attempted than to offer an outline or brief summary of the argument before us. Certain parts of this argument, as the reader will at once perceive, would admit of much amplification; and in any instance in which the genuineness of a particular manuscript, or the authenticity of an ancient work were alleged to be questionable, every part of the evidence would require to be brought forward in all its details, and to be narrowly scrutinized. CHAPTER V. ANCIENT METHODS OF WRITING, AND THE MATERIALS OF BOOKS.