thus the very spirit by which the body is animated, and the signs of
the various affections of the mind, shine out in the countenance.
This superiority of expression in the face some would have
to be an accidental result; they say, that the muscles prepared
for mastication and speaking give such a superiority of muscular
apparatus to the human face, as to account for the superiority
of expression. But I have put that question to rest, by observe
tions and experiments upon the nerves*. That the muscles used
in speaking are those of expression may be readily allowed; but
there are also muscles of expression, which have nothing to do with
the voice, and which are purely indicative by signs of the operations
of the mind. Further, we shall find that the countenance of man
is not merely pre-eminent by the possession of powers peculiar to
him, but also by this, that he stands intermediate betwixt the two
great classes of animals, possessing the muscular system of both
combined.
It is only necessary for the reader to understand that the
muscles are formed of distinct packets of fibres or fasciculi, and
that their extremities are called their origin and insertions: the
fixed extremity, attached generally to some point of bone, is the
origin; the extremity which moves is the insertion of the muscle.
* Philos. Transactions.