De Anima

Aristotle holds that the soul is the form, or essence of any living thing; it is not a distinct substance from the body that it is in. It is the possession of a soul (of a specific kind) that makes an organism an organism at all, and thus that the notion of a body without a soul, or of a soul in the wrong kind of body, is simply unintelligible. (He argues that some parts of the soul — the intellect — can exist without the body, but most cannot.)

In 1855, Charles Collier published a translation titled On the Vital Principle. George Henry Lewes, however, found this description also wanting.