Edward Sapir (18841939). Language: An Introduction to the Study of Speech. 1921.
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: Füsse, Maus: Mäuse. 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 period the mutation was carried through in all dialects. The typical Old High German forms are singular fuoss, plural fuossi;1 singular mus, plural
Note 1. I have changed the Old and Middle High German orthography slightly in order to bring it into accord with modern usage. These purely orthographical changes are immaterial. The u of mus is a long vowel, very nearly like the oo of English moose. [back]