and the native
of the Australian bush indicates extreme closeness of mental similarity
throughout the human species.

When, however, the Englishman and the Australian speak each in his
native tongue, only such words as belong to the interjectional and
imitative classes will be naturally intelligible, and as it were
instinctive to both. Thus the savage, uttering the sound _waow!_ as an
explanation of surprise and warning, might be answered by the white man
with the not less evidently significant _sh!_ of silence, and the two
speakers would be on common ground when the native indicated by the name
_bwirri_ his cudgel, flung _whirring_ through the air at a flock of
birds, or when the native described as a _jakkal-yakkal_ the bird called
by the foreigner a _cockatoo_. With these, and other very limited
classes of natural words, however, resemblance in vocabulary practically
ceases. The Australian and English languages each consist mainly of a
series of words having no apparent connexion with the ideas they
signify, and differing utterly; of course, accidental coincidences and
borrowed words must be excluded from such comparisons. It would be easy
to enumerate other languages of the world, such as Basque, Turkish,
Hebrew, Malay, Mexican, all devoid of traceable resemblance to
Australian and English, and to one another. There is, moreover, extreme
difference in the grammatical structure both of words and sentences in
various languages. The question then arises, how far the employment of
different vocabularies, and that to a great extent on different
grammatical principles, is compatible with similarity of the speakers'
minds, or how far does diversity of speech indicate diversity of mental
nature? The obvious answer is, that the power of using words as signs to
express thoughts with which their sound does not directly connect them,
in fact as arbitrary symbols, is the highest grade of the special human
faculty in language, the presence of which binds together all races of
mankind in substantial mental unity. The measure of this unity is, that
any child of any race can be brought up to speak the language of any
other race.

Under the present standard of evidence in comparing languages and
tracing allied groups to a common origin, the crude speculations as to a
single primeval language of mankind, which formerly occupied so much
attention, are acknowledged to be worthless. Increased knowledge and
accuracy of method have as y