In short, then, compulsion through punishment and the fear of it, though primarily acting on the lower self, does tend, when the conditions of true punishment exist (_i.e._ the reaction of a system of rights violated by one who shares in it), to a recognition of the end by the person punished, and may so far be regarded as his own will, implied in the maintenance of a system to which he is a party, returning upon himself in the form of pain. And this is the theory of punishment as retributive. The test doctrine of the theory may be found in Kant’s saying that, even though a society were about to be dissolved by agreement, the last murderer in prison must be executed before it breaks up. The punishment is, so to speak, his right, of which he must not be defrauded. There are two natural perversions of this theory. The first is to confuse the necessary retribution or reaction of the general self, through the State, with personal vengeance. [1] Even in the vulgar form, when a brutal murder evokes a general desire to have the offender served out, [2] the general or social indignation is not the same as the selfish desire for revenge. It is the offspring of a rough notion of law and humanity, and of the feeling that a striking aggression upon them demands to be strikingly put down. Such a sentiment is a part {228} of the consciousness which maintains the system of rights, and can hardly be absent where that consciousness is strong. [1] It may be noted that Durkheim, relying chiefly on early religious sentiment, denies Maine’s view that criminal law arises out of private feud. [2] Green, _Principles of Political Obligation_, p. 184. The second perversion consists in the superstition that punishment should be “equivalent” to offence. In a sense, we have seen, it is _identical_; _i.e._ it is a return of the offender’s act upon himself by a connection inevitable in a moral organism. But as for _equivalence_ of pain inflicted, either with the pain caused by the offence or with its guilt, the State knows nothing of it and has no means of securing it. It cannot estimate either pain or moral guilt. Punishment cannot be adapted to factors which cannot be known. And further, the attempt to punish for immorality has evils of its own. [1] The graduation of punishments must depend on wholly different principles, which we will consider in speaking of punishment as preventive or deterrent. [1] See above, p. 192.