The consideration of this case leads us to our next point. In all the foregoing cases we presupposed that the speakers of the individual language or of the group-languages were on the whole stationary. We need not here indicate at length the effect upon a community of its migration into regions where other languages are prevalent. The result is commonly a mixed language: and the subject of so-called mixed languages we reserve for another chapter: here we need only remind the student that by such migrations the connection of the language of the emigrants with that of other communities of similar speech is loosened, and the action of differentiating forces, which thus acquire free and unrestricted play, must necessarily be augmented.
The criterion for distinction of dialects among a community of individual languages is, and must be, their phonetic character. Vocabulary and syntax are easily and generally maintained, or, if anything new arises, it may possibly spread over wide areas; but differences of pronunciation and peculiarities of utterance do not necessarily result from the borrowing of new terms.
For instance: a community which pronounces a of father as aw (i.e. like a in all) will do so even when borrowing a word from some dialect in which the pure a is usual.
In conclusion, we must not omit to combat an error too often repeated in books on language which enjoy a reputation otherwise well-deserved. It is a common notion that the tendency to differentiation is, as civilisation advances, replaced by one towards unification; in proof of which we are reminded of the one uniform literary language which, among the educated members of a nation, replaces the various provincial dialects. But this literary language is by no means a regular and natural development of the pre-existing dialects.
One of these, favoured by circumstances political or literary, obtains a supremacy which causes its adoption by those who would otherwise ignore it and continue to speak the dialects of their own provinces, counties, or districts. Hence it is in a certain sense a foreign tongue to them, and though in course of time it may come to replace the indigenous dialect of any district, so that scarcely a trace of the latter remains, it would be misleading to say that this dialect has developed into a language before which it has in reality disappeared.
CHAPTER III.
ON SOUND-CHANGE.
Language is in a constant state of change; and the changes to which it is subject fall under two very different heads. In the first place, new words find their way into a language, whilst existing words become obsolete and drop out of existence: and, secondly, existing words remain, but gradually alter their pronunciation. It is the second of these phenomena which we have to study in this chapter; and a clear idea of its nature, origin, and progress is indispensable to any real knowledge of philology.
To gain this idea we must carefully consider the processes which occur when we speak. We have to take note of no less than five elements, all of which are present each time that we utter a sound, and these should be carefully distinguished.
In the first place, whether we break silence and begin to speak, or proceed in the course of speaking to any particular sound, our vocal organs must move towards a certain position, in which they must remain during the time of the utterance of the sound. This is equally true whether they are set in motion after a period of rest, or after a position rendered necessary by their utterance of some other sound. Let us take, for instance, the sound which in the word father we represent by the letter a. In pronouncing this WORD we BEGIN by putting our lips, tongue, vocal chords, etc., all in such a position that, on the breath passing through them or coming into contact with them, the sound represented by f is produced; and as long as the vocal organs remain in that position, nothing but f can be pronounced. In order, then, to pronounce the a sound, we must alter the position of our vocal organs: our vocal chords must be approximated, our lips relaxed, our mouth opened wider, until the a position is attained. It is clear that the course which we take to reach our goal depends not merely upon the position of that goal, but likewise upon the point whence we start to reach it. Hence the course whereby we reach this a position will vary constantly and considerably, seeing that in our utterance of the a sound we can and do cause many other sounds to precede it. But all these movements agree in one respect, that they terminate in a certain position, which we maintain as long as the a sound lasts.