 In addition to its role within ancient philosophy and cosmology, teleology has long been an important topic within physiology and medicine. Galen’s On the Use of the Parts (De usu partium) is an early example of teleological reasoning applied to physiology (see the section on teleology in the entry on  Galen).  In this text, Galen presents a functional analysis of the various parts of living organisms, in which “existence, structure, and attributes of all the parts must be explained by reference to their functions in promoting the activities of the whole organism” (Schiefsky 2007: 371). For Galen, a teleological account of parts is superior to a purely causal-mechanical one, since the function or purpose of the part plays an ineliminable role in the explanation of the part and its activities. This Galenic view of anatomy, with its explicitly Aristotelian reliance on final causes, largely dominated medical thought until the seventeenth century. William Harvey’s On the Motion of the Heart and Blood (De motu cordis) was seen by many of his contemporaries (e.g., Hobbes, Descartes) as a turning point away from the Galenic or Aristotelian approaches to anatomy, with their appeal to final causes, toward the new mechanistic and experimental science of the seventeenth century (French 1994).  His attempt to empirically establish the structure and motion of the heart without ever claiming to have identified the final cause of circulation, as well as his use of mechanical analogies, such as the analogy from the expansion of the arteries to the inflation of a glove, provide some support for this assessment. Robert Boyle, however, offered a different interpretation of Harvey’s work. Boyle saw it as amenable to his ‘compatibilist’ approach that attempted to show that “mechanical and teleological explanations of biological phenomena are compatible” (Lennox 1983: 38).  Recent commentators have also suggested Harvey was strongly influenced by Aristotelian teleological thinking, and thus is a liminal figure in the transition from vitalist to purely mechanistic explanation in physiology and medicine (Distelzweig 2014, 2016; Lennox 2017), although Lennox notes that “Harvey appears to be pressing the analogy between art and nature in ways that are not Aristotelian but more Platonic in spirit” (Lennox 2017: 191). 