Aristotle, following Plato, defined the soul as the core essence of a living being, but argued against its having a separate existence. For instance, if a knife had a soul, the act of cutting would be that soul, because 'cutting' is the essence of what it is to be a knife. Unlike Plato and the religious traditions, Aristotle did not consider the soul as some kind of separate, ghostly occupant of the body (just as we cannot separate the activity of cutting from the knife).