Aristotle On Breath (ch. 8‒21) (translation by Svetlana V. Mesyats)

Abstract

The publication contains the second part of Aristotle’s treatise “On Respiration” (chapters 8‒21), in which Aristotle moves from criticizing previous theories of respiration to the presentation of his own doctrine, which can be reduced to two points: (1) not all animals breathe, but only those that have lungs; (2) animals need breathing for cooling. Since being alive means to eat and grow, and the fulfillment of both these functions requires fire, all living creatures, according to Aristotle, have some kind of “innate natural heat”, which must be constantly cooled down so that it does not become excessive and would not lead a living creature to death. In animals with blood, the source of this inner fire is the heart, and in bloodless ones, the central part of the body, which is analogous to it. To prevent the fire in the heart from fading away, animals must be constantly cooled either from the outside by their environment, or from the inside – by passing the environment through themselves. Whereas the first method is typical for bloodless creatures, the second is characteristic of animals with blood, which can let through them either air or water, depending on the environment in which they live. Animals that let air through them have lungs and breathe, while those that let water through have gills and lack breath. The development of this doctrine of respiration allowed Aristotle to find out the causes of natural and violent death and to define the different stages of animal’s life cycle, including birth and death, youth and old age, as well as to come close to the principles of medical art and understanding the causes of cardiac activity.