To put one extreme case, about the soul he could think at first in the Eudemus like Plato that it is imprisoned in the body, and long afterwards in the De Anima like himself that it is the immateriate essence of the material bodily organism.
Like any natural substance, he is composed of matter and immateriate essence.
Soul is not an immateriate essence of an organic body capable, but an immateriate conscious substance within an organic body.
Each natural substance is a compound (ov6Erov, vuvNTn ouvia) of essence and matter; its essence (Ethos, i top01 7, Tò TL krL, TOri i i' Etva6) being its actual substance, its matter (An) not; its essence being determinate, its matter not; its essence being immateriate, its matter conjoined with the essence; its essence being one in all individuals of a species, its matter different in each individual; its essence being cause of uniformity, its matter cause of accident.
