ed of one or more of
the senses. It is substantially a fragment, and a very important
fragment, on AEsthetics, and as such there will be something to say about
it in another chapter. But there are, perhaps, one or two points at
which the Letter on the Deaf and Dumb touches the line of thought of the
Letter on the Blind.

The Letter opens on the question of the origin and limits of inversion
in language. This at once leads to a discussion of the natural order of
ideas and expressions, and that original order, says Diderot, we can
only ascertain by a study of the language of gesture. Such a study can
be pursued either in assiduous conversation with one who has been deaf
and dumb from birth, or by the experiment of a _muet de convention_, a
man who foregoes the use of articulate sounds for the sake of experiment
as to the process of the formation of language. Generalising this idea,
Diderot proceeds to consider man as distributed into as many distinct
and separate beings as he has senses. "My idea would be to decompose a
man, so to speak, and to examine what he derives from each of the senses
with which he is endowed. I have sometimes amused myself with this kind
of metaphysical anatomy; and I found that of all the senses, the eye was
the most superficial; the ear, the proudest; smell, the most voluptuous;
taste, the most superstitious and the most inconstant; touch, the
profoundest and the most of a philosopher. It would be amusing to get
together a society, each member of which should have no more than one
sense; there can be no doubt that they would all treat one another as
out of their wits."

This is interesting, because it was said at the time to be the source of
one of the most famous fancies in the philosophical literature of the
century, the Statue in Condillac's Treatise on the Sensations. Condillac
imagined a statue organised like a man, but each sense unfolding itself
singly, at the will of an eternal arbiter. The philosopher first admits
the exercise of smell to his Frankenstein, and enumerates the mental
faculties which might be expected to be set in operation under the
changing impressions made upon that one sense. The other senses are
imparted to it in turn, one by one, each adding a new group of ideas to
the previous stock, until at length the mental equipment is complete.

We may see the extent of the resemblance between Condillac's Statue and
Diderot's _muet de convention_, but Diderot at least is free