case may not be of the least use. Such habitual movements are often,
or generally inherited; and they then differ but little from reflex actions.
When we treat of the special expressions of man, the latter part of our
first Principle, as given at the commencement of this chapter, will be
seen to hold good; namely, that when movements, associated through habit
with certain states of the mind, are partially repressed by the will,
the strictly involuntary muscles, as well as those which are least
under the separate control of the will, are liable still to act;
and their action is often highly expressive. Conversely, when the will
is temporarily or permanently weakened, the voluntary muscles fail
before the involuntary. It is a fact familiar to pathologists,
as Sir C. Bell remarks,[20] "that when debility arises from affection
of the brain, the influence is greatest on those muscles which are,
in their natural condition, most under the command of the will."
We shall, also, in our future chapters, consider another proposition
included in our first Principle; namely, that the checking of one habitual
movement sometimes requires other slight movements; these latter serving
as a means of expression.


[19] See the account given by this excellent observer in `Wild Sports
of the Highlands,' 1846, p. 142.


[20] `Philosophical Translations,' 1823, p. 182.



CHAPTER II.