impenetrable the barriers between two groups the more
will the languages differ, and the less mutually intelligible will
they be.

Looking back over the history of language the student of
linguistics infers that those languages which bear striking or
significant similarities are related. Thus Spanish, Italian,
French, Portuguese, and Roumanian are traceable directly
back to the Latin. This does not mean that all over the areas
occupied by the speakers of these languages Latin was originally
spoken. But the Romans in their conquests, both military
and cultural, were able to make their own language
predominant. The variations which make French and Roumanian,
say, mutually unintelligible, are due to the fact that
Latin was for the natives in these conquered territories
assimilated to their own languages. So that, in the familiar
example, the Latin "homo" becomes "uomo" in Italian,
"homme" in French, "hombre" in Spanish, and "om" in
Roumanian. Similarly related but mutually unintelligible
languages among the American Indians have been traced to
three great source-languages.

The history of European languages offers an interesting
example of differentiation. English and German, for example,
are both traceable back to West-Germanic; from that
in turn to a hypothecated primitive West-Germanic. All
the European languages are traceable back to a hypothecated
Primitive Indo-European.[1] The theory held by most
students of this subject is that the groups possessing this
single uniform language spread over a wider and wider area,
gradually became separated from each other by geographical
barriers and tribal affiliations, and gradually (and on the
part of individual speakers unconsciously) modified their
speech so that slight differences accumulated, and resulted
finally in widely different and mutually unintelligible
languages.

[Footnote 1: By the word "primitive" the linguistic experts
mean a language the existence of which is inferred from common
features of several related languages, of which written records
are current, but of which no actual records exist. Thus, if
there were no written records of Latin the approximate
reconstruction of it by linguists would be called "Primitive
Romance."]

The process of differentiation in the languages of different
groups is very marked. We find, for example, in the early
history of Greece and Rome, a number of widely different
dialects. There seems every evidence that these wer