''Movement of Animals'' (or ''On the Motion of Animals''; Greek Περὶ ζῴων κινήσεως; Latin ''De Motu Animalium'') is one of

Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of phil ...

's major texts on biology. It sets out the general principles of

animal locomotion Animal locomotion, in ethology, is any of a variety of methods that animal (biology), animals use to move from one place to another. Some modes of locomotion are (initially) self-propelled, e.g., running, swimming, jumping, flying, hopping, soari ...

Pneuma

All animals "possess an inborn spirit (''pneuma sumphuton'') and exercise their strength in virtue of it." (703a10). This inborn spirit is used to explain desire (''orexis''), which is classified as the "central origin (''to meson''), which moves by being itself moved." (703a5-6). 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). The inborn ''pneuma'' is, likewise, tethered to the soul, or as he says here, ''tēn'' ''arche tēn psuchikēn, "''the origin of the soul," the soul as the center of causality. This "spirit" is not the soul itself but a limb of the soul that helps it move. The inborn spirit causes movement in the body by expanding and contracting. Each of these implies not only a movement but also a change in the degree of power and strength of the animal. "when it contracts it is without force, and one and the same cause gives it force and enables it to thrust" (703a23). Compare this to the view that is developed in ''On Sleeping and Waking'', namely, the view "that has been laid down that sense-perception originates in the same part of an animal's body as movement does. ..In sanguineous animals this is the region about the heart; for all sanguineous animals possess a heart, and both movement and the dominant sense-perception originate there. 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. We will discuss this later on. In bloodless animals and insects and creatures which do not respire, the naturally inherent breath is seen expanding and contraction in the part which corresponds to the heart in other animals" (456a1-13). "Since it is impossible to make any movement, or do any action without strength, and the holding of the breath produces strength" (456a17).

Editions and translations

* *
On the Motion of Animals
', translated by A. S. L. Farquharson * *
De Motu and De Incessu Animalium
', translated by A. S. L. Farquharson (Internet Archive) *

Martha Nussbaum Martha Craven Nussbaum (; born May 6, 1947) is an American philosopher and the current Ernst Freund Distinguished Service Professor of Law and Ethics at the University of Chicago, where she is jointly appointed in the law school and the philosoph ...

, ''Aristotle's De Motu Animalium''. Princeton University Press, 1978 . Animal locomotion Works by Aristotle Zoology books {{zoology-book-stub