BOOK THE THIRD.
CHAPTER I.
Note 1, p. 131. The sentient organs, however, are con-
stituted, &c.] The senses were formed, according to that
age, from the elements—as the hearing from air, and the
eye, which alone was supposed to have a special organ,
from the purest part of the fluid secreted by the brain; and
vision is the result, according to Aristotle, of refraction.
Thus, Democritus[1] was held to be right in saying that the
eye is water but to be wrong in supposing vision to be
caused by reflection, (τὸ ὁρᾶν εἶναι τὴν ἔμφασιν) as vision
is, not in the eye but, in the percipient; for "vision is re-
fraction" (ἀνάκλασις γὰρ τὸ πάθος). Aristotle shews that,
according to the admitted doctrines, these two elements
only constitute the sentient organs of all animals which
are perfect; and adds, as if to guard against a possible
objection, that the mole has eyes although they may not
be very apparent. It is then argued that, unless there is
some kind of body or mode of impression different from all
- ↑ De Sensu et Sens. 2. 10.
