is the soul part of the body function?

Ancient philosophical theories of soul are in many respects sensitive to ways of speaking and thinking about the soulthat are not specificaly philosophical or teoretical. We therefore begin with what the word ‘soul’ meant to speakers of Classical Greek, and what it would have been natural to think about and associate with the soul. We then turn to various Presocratic thinkers, and to the philosophical theories that are our primary concern, those of Plato, Aristotle. These are by far the most carefully worked out theories of soul in ancient philosophy. Later theoretical developments for instance, in the writings of Plotinus and other Platonists, as well as the Church Fathers are best studied against the background of the classical theories, from which, in large part, they derive.
From comparatively humble Homeric beginnings, the word ‘soul’ undergoes quite remarkable semantic expansion in sixth and fifth century usage. By the end of the fifth century the time of Socrates' death soul is standardly thought and spoken of, for instance, as the distinguishing mark of living things, as something that is the subject of emotional states and that is responsible for planning and practical thinking, and also as the bearer of such virtues as courage and justice. Coming to philosophical theory, we first trace a development towards comprehensive articulation of a very broad conception of soul, according to which the soul is not only responsible for mental or psychological functions like thought, perception and desire, and is the bearer of moral qualities, but in some way or other accounts for all the vital functions that any living organism performs. This broad conception, which is clearly in close contact with ordinary Greek usage by that time, finds its fullest articulation in Aristotle's theory. The theories of the Hellenistic period, by contrast, are interested more narrowly in the soul as something that is responsible specifically for mental or psychological functions. They either de emphasize or sever the ordinary language connection between soul and life in all its functions and aspects.