Now for Reiffenstuel's reason. "The reason," he says, "is, because in such a case as is supposed the acceptance and offering of a duel is an absolutely necessary, and thereby a just and lawful, defence of your reputation, or goods of fortune, and, by equivalence, even of your life, against an unjust aggressor, who we suppose does you an injury, and thereby gives you no choice but to call him out, or calls you out, and accordingly assails you in words, &c. Hence, as for the needful defence of reputation, or of goods of fortune of great consequence, it is lawful, with the moderation of a blameless defence, to kill an unjust aggressor, so it will be also lawful to offer and accept a duel, and therein slay the other party." Reiffenstuel here evidently supposes that killing done in self-defence is _direct_. Those who agree with him on that point, proceed to draw differences between self-defence and accepting a challenge. Of course the two are not the same. The true difficulty for them lies in making out how the reasons which justify self-defence in their view of it, do not also justify the acceptance of a duel: how, if I may make another man's death a means to the preservation of my vital right, I may not as well make another man's risk of death and my own, which is all that a duel amounts to, also a _means_, none other being at hand, to the preserving of my no less vital right. This grave objection does not touch us. We have denied that killing in self-defence is direct. On the lines of that denial we meet Reiffenstuel's argument simply as follows. 3. In self-defence, the aggressor is slain _indirectly_. In a duel, not indeed the death itself, or mutual slaughter of the combatants, is _directly_ willed, but the risk of mutual slaughter is directly willed. But we may not directly will the risk of that which we may not directly do. And the combatants may not directly do themselves or one another to death. Therefore they may not directly risk each his own and his antagonist's life. But this risk is of the essence of a duel. Therefore duelling is essentially unlawful.