[Pages 114–115] [H]e [Aristotle] tells us expressly, that that which we call the rational soul is […] 'separable from the body,' […] 'because it is not the entelech of any body.' […] [page 500] Wickedness is the form and entelech of all the wicked spirits: it is the difference of a name, rather than any proper difference of natures that is between the devil and wicked men.
Source: wiktionary