87. Into this controversy of theologians on the origin of the human soul has entered the philosophic dispute on _the origin of forms._ Aristotle and scholastic philosophy after him called _Form_ that which is a [170] principle of action and is found in that which acts. This inward principle is either substantial, being then termed 'Soul', when it is in an organic body, or accidental, and customarily termed 'Quality'. The same philosopher gave to the soul the generic name of 'Entelechy' or _Act_. This word 'Entelechy' apparently takes its origin from the Greek word signifying 'perfect', and hence the celebrated Ermolao Barbaro expressed it literally in Latin by _perfectihabia_: for Act is a realization of potency. And he had no need to consult the Devil, as men say he did, in order to learn that. Now the Philosopher of Stagira supposes that there are two kinds of Act, the permanent act and the successive act. The permanent or lasting act is nothing but the Substantial or Accidental Form: the substantial form (as for example the soul) is altogether permanent, at least according to my judgement, and the accidental is only so for a time. But the altogether momentary act, whose nature is transitory, consists in action itself. I have shown elsewhere that the notion of Entelechy is not altogether to be scorned, and that, being permanent, it carries with it not only a mere faculty for action, but also that which is called 'force', 'effort', 'conatus', from which action itself must follow if nothing prevents it. Faculty is only an _attribute_, or rather sometimes a mode; but force, when it is not an ingredient of substance itself (that is, force which is not primitive but derivative), is a _quality_, which is distinct and separable from substance. I have shown also how one may suppose that the soul is a primitive force which is modified and varied by derivative forces or qualities, and exercised in actions.