[Footnote 122:  In so far as they do not fall out of the normal speech group by reason of a marked speech defect or because they are isolated foreigners that have acquired the language late in life.]

If the speech of any member of the series could actually be made to fit into another dialect series,[123] we should have no true barriers between dialects (and languages) at all.  We should merely have a continuous series of individual variations extending over the whole range of a historically unified linguistic area, and the cutting up of this large area (in some cases embracing parts of several continents) into distinct dialects and languages would be an essentially arbitrary proceeding with no warrant save that of practical convenience.  But such a conception of the nature of dialectic variation does not correspond to the facts as we know them.  Isolated individuals may be found who speak a compromise between two dialects of a language, and if their number and importance increases they may even end by creating a new dialectic norm of their own, a dialect in which the extreme peculiarities of the parent dialects are ironed out.  In course of time the compromise dialect may absorb the parents, though more frequently these will tend to linger indefinitely as marginal forms of the enlarged dialect area.  But such phenomena—­and they are common enough in the history of language—­are evidently quite secondary.  They are closely linked with such social developments as the rise of nationality, the formation of literatures that aim to have more than a local appeal, the movement of rural populations into the cities, and all those other tendencies that break up the intense localism that unsophisticated man has always found natural.

[Footnote 123:  Observe that we are speaking of an individual’s speech as a whole.  It is not a question of isolating some particular peculiarity of pronunciation or usage and noting its resemblance to or identity with a feature in another dialect.]

The explanation of primary dialectic differences is still to seek.  It is evidently not enough to say that if a dialect or language is spoken in two distinct localities or by two distinct social strata it naturally takes on distinctive forms, which in time come to be divergent enough to deserve the name of dialects.  This is certainly true as far as it goes.  Dialects do belong, in the first instance, to very definitely circumscribed social groups, homogeneous enough to secure the common feeling and purpose needed to create a norm.  But the embarrassing question immediately arises, If all the individual variations within a dialect are being constantly leveled out to the dialectic norm, if there is no appreciable tendency for the individual’s peculiarities to initiate a dialectic schism, why should we have dialectic variations at all?  Ought not the norm, wherever and whenever threatened, automatically to reassert itself?  Ought not the individual variations of each locality, even in the absence of intercourse between them, to cancel out to the same accepted speech average?