The voluntary, then, seems opposed to the involuntary, and to act with knowledge of the person acted on, instrument and aim for sometimes one knows the object, eg as father, but not that the aim of the act is to kill, not to save, as in the case of Pelias's daughters; or knows the object to be a drink but takes it to be a philtre or wine when it was really hemlock seems opposed to action in ignorance of the person, instrument, or thing, if, that is, the action is essentially the effect of ignorance.