As, then, that which is involuntary is in two parts, one depending on force, the other on ignorance, that which is voluntary is the opposite of both. For that which is voluntary is the result neither of force nor of ignorance Ibid., ch. 32.. A voluntary act, then, is one of which the beginning or cause originates in an actor, who knows each individual circumstance through which and in which the action takes place. By “individual” is meant what the rhetoricians call circumstantial elements: for instance, the actor, the sufferer, the action (perchance a murder), the instrument, the place, the time, the manner, the reason of the action.