Early Stoic philosophy concerned itself to a great extent with physical science. Much of the Stoics’ interest in this general topic originated from their theories about the interconnectivity and materiality of all things (see Sambursky 1959). The Stoics, however, never developed a systematic approach to human biology and anatomy or an account of the human body akin to, for example, the one we find in Plato’s Timaeus. This comes as a surprise, especially given that Stoicism’s founder, Zeno (334-262 B.C.), was a near exact contemporary of the physician Herophilus of Chalcedon (330-260 B.C.), who, while working at the Ptolemaic court in Alexandria, was making great advances in anatomical methods and using them to investigate bodily systems (Solmsen 1961; von Staden 1989; Hankinson 2003). The Stoics’ lack of engagement with anatomy as a physical science may lie in their ideas about total mixture and continuum. The Stoics declined to see a body as an entity composed of strictly defined and separable parts and instead championed the notion that “man does not consist of more parts than his finger, nor the world than man... [we should] think of each body as consisting neither of certain parts nor of some number of them, either infinite or finite” (Plut.de comm. not.1079a10-1079c6 = Long & Sedley 50C). Developments in anatomical science did, however, have an impact on Stoic thought. Explorations into the human body by the Alexandrian anatomists necessitated the creation of special terms and figurative language to describe their findings (von Staden 1989). Herophilean anatomical descriptions of the circulatory and nervous systems and of sensory perception, in particular, provided to the Stoics a new vocabulary that was readily applicable to ideas about mixture, continuum, and interconnectivity.
Herophilus, for example, used a spider web as an analogy for the sensory membranes of both the eye and the skin (von Staden T 74, 88) and supplemented this figurative language with empirical analysis of the biological infrastructure associated with each organ. The Stoics used the spider’s web as an image which represented the total connectivity of the world, originating with an organism’s central hegemonikon and extending to external stimuli by means of pneuma (Calcid.Ad Timaeum.cp.220 = SVF 2.879.31-37).
The Stoics viewed the entire material world, animal bodies included, as a “co-flowing” and “co-breathing” organism. Yet, the Stoics could not ignore the findings of Alexandrian anatomists like Herophilus who had successfully investigated the body as a composite substance comprised of isolatable parts and systems. Through a consideration of the Stoic appropriation of anatomical language a clearer picture emerges of the relationship between medicine and philosophy in the early Hellenistic period. Furthermore, we find that such a relationship extends across epistemological boundaries through its dual engagement with biological empiricism and language.