On The Soul
air acting and being acted upon, so long as it maintains an unbroken
unity. That is why in the case of reflection it is better, instead
of saying that the sight issues from the eye and is reflected, to
say that the air, so long as it remains one, is affected by the
shape and colour. On a smooth surface the air possesses unity; hence
it is that it in turn sets the sight in motion, just as if the
impression on the wax were transmitted as far as the wax extends.
It is clear that the body of an animal cannot be simple, i.e.
consist of one element such as fire or air. For without touch it is
impossible to have any other sense; for every body that has soul in it
must, as we have said, be capable of touch. All the other elements
with the exception of earth can constitute organs of sense, but all of
them bring about perception only through something else, viz.
through the media. Touch takes place by direct contact with its
objects, whence also its name. All the other organs of sense, no
doubt, perceive by contact, only the contact is mediate: touch alone
perceives by immediate contact. Consequently no animal body can
consist of these other elements.
Nor can it consist solely of earth. For touch is as it were a mean
between all tangible qualities, and its organ is capable of
receiving not only all the specific qualities which characterize
earth, but also the hot and the cold and all other tangible
qualities whatsoever. That is why we have no sensation by means of
bones, hair, &c., because they consist of earth. So too plants,
because they consist of earth, have no sensation. Without touch
there can be no other sense, and the organ of touch cannot consist
of earth or of any other single element.
It is evident, therefore, that the loss of this one sense alone must
bring about the death of an animal. For as on the one hand nothing