Movement of Animals

Movement of Animals (or On the Motion of Animals; Greek Περὶ ζῴων κινήσεως; Latin De Motu Animalium) is one of Aristotle's major texts on biology.

All animals "possess an inborn spirit (pneuma sumphuton) and exercise their strength in virtue of it."

Aristotle furthers this idea of being a "middle cause" by furnishing the metaphor of the movement of the elbow, as it relates to the immobility of the shoulder (703a13).

Each of these implies not only a movement but also a change in the degree of power and strength of the animal.

As for movement, it is clear that breathing and in general the process of cooling takes its rise here, and that nature has supplied both breathing and the power of cooling by moisture with a view to the conservation of the heat in that part.