Holding as we do that, while knowledge of any kind is a thing to
be honoured and prized, one kind of it may, either by reason of its
greater exactness or of a higher dignity and greater wonderfulness
in its objects, be more honourable and precious than another, on both
accounts we should naturally be led to place in the front rank the
study of the soul. The knowledge of the soul admittedly contributes
greatly to the advance of truth in general, and, above all, to our
understanding of Nature, for the soul is in some sense the principle
of animal life. Our aim is to grasp and understand, first its essential
nature, and secondly its properties; of these some are taught to be
affections proper to the soul itself, while others are considered
to attach to the animal owing to the presence within it of soul.
To attain any assured knowledge about the soul is one of the most
difficult things in the world. …
Aristotle, De Anima, BOOK I, Part 1.
Aristotle's Idea of the Soul considers that whilst various collections of materials, (Matter), may have potential for life as a plant, or as an animal,
it is Soul, (referred to as Form), which is required to provide necessary capacities for actualisation of that potential for life.
The soul is the first actuality of a natural body that has life potentially.
Aristotle, De Anima 412a27
… the soul neither exists without a body nor is a body of some sort. For it is not a body, but it belongs to a body, and for this reason
is present in a body, and in a body of such-and-such a sort …
Aristotle, De Anima 414a20
Aristotle's Ideas on the Soul and Body allows that Soul will differ in that the "Form" of any living plant, or animal, will bear a full
relationship to the type of living thing it is.
Aristotle's Idea of Soul recognises the existence three types of soul functionality.
Functionality related to the intake of nutrients, the growth of the plant or animal, and its behavior related to its reproduction.
Functionality related to movement and perception.
Functionality that is associated with actual processes of thought.
Aristotle attributes Nutritive soul capacities to all plants, animals and Humans.
He also attributes Sensitive soul capacities, (related to movement and perception), to animals and Humans.
And Rational soul capacities, (related to thought and other intellectual behaviors), to Humans only.
Key sources supportive of
Tripartite Soul Theory