growth, indicating the stage to which the language has attained. A
proper case system may not have been established in a language by the
fixing of case particles, or, having been established, it may change by
the increase or diminution of the number of cases. A tense system also
has a beginning, a growth, and a decadence. A mode system is variable in
the various stages of the history of a language. In like manner a
pronominal system undergoes changes. Particles may be prefixed, infixed,
or affixed in compounded words, and which one of these methods will
finally prevail can be determined only in the later stage of growth. All
of these things are held to belong to the grammar of a language and to
be grammatic methods, distinct from lexical elements.

With terms thus defined, languages are supposed to be cognate when
fundamental similarities are discovered in their lexical elements. When
the members of a family of languages are to be classed in subdivisions
and the history of such languages investigated, grammatic
characteristics become of primary importance. The words of a language
change by the methods described, but the fundamental elements or roots
are more enduring. Grammatic methods also change, perhaps even more
rapidly than words, and the changes may go on to such an extent that
primitive methods are entirely lost, there being no radical grammatic
elements to be preserved. Grammatic structure is but a phase or accident
of growth, and not a primordial element of language. The roots of a
language are its most permanent characteristics, and while the words
which are formed from them may change so as to obscure their elements or
in some cases even to lose them, it seems that they are never lost from
all, but can be recovered in large part. The grammatic structure or plan
of a language is forever changing, and in this respect the language may
become entirely transformed.