The ensouled is distinguished from the unsouled by its being alive. Now since being alive is spoken of in many ways, even if only one of these is present, we say that the thing is alive, if, for instance, there is intellect or perception or spatial movement and rest or indeed movement connected with nourishment and growth and decay. It is for this reason that all the plants are also held to be alive . . .
The observer of the soul cannot penetrate into the soul, but there doubtless is a margin where he comes into contact with it. Recognition of this contact is the fact that even the soul does not know of itself. Hence it must remain unknown. That would be sad only if there were anything apart from the soul, but there is nothing else.