effects motion is obviously corporeal, its nature must be studied together with those functions which are common to the body and the Vital Principle. But to speak summarily, the organism whereby motion is effected, is as a hinge in which coexist the beginning and the end of motion—for herein are the convex and the concave, of which that is the beginning, and this the end of motion; and therefore the one is at rest while the other is in motion, as although, rationally considered, the two pieces are distinct, yet, substantively, they are inseperable.
In fine, then, as has been said, an animal is endowed with self-motion to the extent of its appetition; but it cannot be susceptible of appetite without imagination, and all imagination is either rational or sentient, and of this latter kind other animals partake also.
