Abstract

The Stoics defined the human soul in two ways: both as a homogeneous, unified and entirely rational substance (the so-called 'psychological monism' of Chrysippus), and as a corporeal entity, a warm breath spread throughout the body, whose permeability with the body can be seen in the theory of exhalation (anathumiasis). The aim of this article is to understand how the Stoics manage to maintain their promise of absolute freedom for the rational faculty, while at the same time making it permeable to the bodily conditions that are its own - that is, the internal and external temperature, and any modifications introduced by the body's own physiology. The article explores the psychologies of Zeno, Cleanthes and Chrysippus, particularly in their borrowings from Heraclitus and Aristotle, and then focuses on the phenomenon of exhalation, in the developments proposed by Diogenes of Babylonia and Posidonius, thus presenting new tools for shaping the rational soul.