192. The answer is: As regards heaviness of punishment, it is not in the power of the state to regulate the amount of pain which it causes to the person whom it punishes. If it could only punish justly by making this pain proportionate in each case to the depravity implied in the crime, it could not punish justly at all. The amount of pain which any kind of punishment causes to the particular person depends on his temperament and circumstances, which neither the state nor its agent, the judge, can ascertain. But if it could be ascertained, and if (which is equally impossible) the amount of depravity implied in each particular crime could be ascertained likewise in order to make the pain of the punishment proportionate to the depravity, a different punishment would have to be inflicted in each case according to the temperament and circumstances of the criminal. There would be an end to all general rules of punishment. 193. In truth, however, the state in its capacity as the sustainer of rights (and it is in this capacity that it punishes) has nothing to do with the amount of moral depravity in the criminal, and the primary reference in punishment, as inflicted by the state, is not to the effect of the punishment on the person punished but to its effect on others. The considerations determining its amount should be prospective rather than retrospective. In the crime a right has been violated. No punishment can undo what has been done, or make good the wrong to the person who has suffered. What it can do is to make less likely the doing of a similar wrong in other cases. Its object, therefore, is not to cause pain to the criminal for the sake of causing it, nor chiefly for the sake of preventing him, individually, from committing the crime again, but to associate terror with the contemplation of the crime in the mind of others who might be tempted to commit it. And this object, unlike that of making the pain of the punishment commensurate with the guilt of the criminal, is in the main attainable. The effect of the spectacle of punishment on the onlooker is independent of any minute inquiry into the degree to which it affects the particular criminal. The attachment of equal penalties to offences that are alike in respect of the importance of the rights which they violate, and in respect of the ordinary temptations to them, will, on the whole, lead to the association of an equal amount of terror with the prospect of committing like offences in the public mind. When the circumstances, indeed, of two criminals guilty of offences alike in both the above respects are very greatly and obviously different, so different as to make the operation of the same penalty upon them very conspicuously different, then the penalty may be varied without interfering with its terrifying effect on the public mind. We will suppose e.g. that a fraud on the part of a respectable banker is equivalent, both in