may have listened, the movements of these organs have become
firmly associated together through long-continued habit.

Dr. Piderit published in 1859 an essay on Expression, which I
have not seen, but in which, as he states, he forestalled
Gratiolet in many of his views. In 1867 he published his
`Wissenschaftliches System der Mimik und Physiognomik.' It is hardly
possible to give in a few sentences a fair notion of his views;
perhaps the two following sentences will tell as much as can
be briefly told: "the muscular movements of expression are
in part related to imaginary objects, and in part to imaginary
sensorial impressions. In this proposition lies the key
to the comprehension of all expressive muscular movements."
(s. 25) Again, "Expressive movements manifest themselves
chiefly in the numerous and mobile muscles of the face,
partly because the nerves by which they are set into motion originate
in the most immediate vicinity of the mind-organ, but partly
also because these muscles serve to support the organs of sense."
(s. 26.) If Dr. Piderit had studied Sir C. Bell's work,
he would probably not have said (s. 101) that violent
laughter causes a frown from partaking of the nature of pain;
or that with infants (s. 103) the tears irritate the eyes,
and thus excite the contraction of the surrounding in muscles.
Many good remarks are scattered throughout this volume,
to which I shall hereafter refer.

Short discussions on Expression may be found in various works,
which need not here be particularised. Mr. Bain, however,
in two of his works has treated the subject at some length.
He says,[8] "I look upon the expression so-called as part and parcel