I have preferred to take up in some detail the analysis of our hesitation in using a locution like “Whom did you see?” and to point to some of the English drifts, particular and general, that are implied by this hesitation than to discuss linguistic change in the abstract.  What is true of the particular idiom that we started with is true of everything else in language.  Nothing is perfectly static.  Every word, every grammatical element, every locution, every sound and accent is a slowly changing configuration, molded by the invisible and impersonal drift that is the life of language.  The evidence is overwhelming that this drift has a certain consistent direction.  Its speed varies enormously according to circumstances that it is not always easy to define.  We have already seen that Lithuanian is to-day nearer its Indo-European prototype than was the hypothetical Germanic mother-tongue five hundred or a thousand years before Christ.  German has moved more slowly than English; in some respects it stands roughly midway between English and Anglo-Saxon, in others it has of course diverged from the Anglo-Saxon line.  When I pointed out in the preceding chapter that dialects formed because a language broken up into local segments could not move along the same drift in all of these segments, I meant of course that it could not move along identically the same drift.  The general drift of a language has its depths.  At the surface the current is relatively fast.  In certain features dialects drift apart rapidly.  By that very fact these features betray themselves as less fundamental to the genius of the language than the more slowly modifiable features in which the dialects keep together long after they have grown to be mutually alien forms of speech.  But this is not all.  The momentum of the more fundamental, the pre-dialectic, drift is often such that languages long disconnected will pass through the same or strikingly similar phases.  In many such cases it is perfectly clear that there could have been no dialectic interinfluencing.

These parallelisms in drift may operate in the phonetic as well as in the morphological sphere, or they may affect both at the same time.  Here is an interesting example.  The English type of plural represented by foot:  feet, mouse:  mice is strictly parallel to the German Fuss:  Fuesse, Maus:  Maeuse.  One would be inclined to surmise that these dialectic forms go back to old Germanic or West-Germanic alternations of the same type.  But the documentary evidence shows conclusively that there could have been no plurals of this type in primitive Germanic.  There is no trace of such vocalic mutation ("umlaut”) in Gothic, our most archaic Germanic language.  More significant still is the fact that it does not appear in our oldest Old High German texts and begins to develop only at the very end of the Old High German period (circa 1000 A.D.).  In the Middle High German