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?

If individual variations "on a flat" were the only kind of variability
in language, I believe we should be at a loss to explain why and how
dialects arise, why it is that a linguistic prototype gradually breaks
up into a number of mutually unintelligible languages. But language is
not merely something that is spread out in space, as it were--a series
of reflections in individual minds of one and the same timeless picture.
Language moves down time in a current of its own making. It has a drift.
If there were no breaking up of a language into dialects, if each
language continued as a firm, self-contained unity, it would still be
constantly movin