From all that has gone before a general theorem may be deduced, of great utility, though little comformable to custom, that common lawgiver of nations. The theorem is this: In order that every punishment may not be an act of violence, committed by one man or by many against a single individual, it ought to be above all things public, speedy, necessary, the least possible in the given circumstances, proportioned to its crime, dictated by the laws.

The very severity of a punishment leads men to dare so much the more to escape it, according to the greatness of the evil in prospect; and many crimes are thus committed to avoid the penalty of a single one. Countries and times where punishments have been most severe have ever been those where the bloodiest and most inhuman deeds have been committed, the same spirit of ferocity that guided the hand of the legislator having guided also that of the parricide and assassin; on the throne dictating iron[168] laws for the villanous souls of slaves to obey, and in the obscurity of private life urging to the slaughter of tyrants, only to create fresh ones in their stead.

Whoever kills himself does a lesser evil to society than he who for ever leaves the boundaries of his country, for whilst the former leaves therein all his substance, the latter transports himself together with part of his property. Nay, if the power of a community consists in the number of its members, the man who withdraws himself to join a neighbouring nation does twice as great an injury as he who simply by death deprives society of his existence. The question, therefore, reduces itself to this: whether the leaving to each member of a nation a perpetual liberty to absent himself from it be advantageous or detrimental.

If pleasure and pain are the motors of sensitive beings, if the invisible lawgiver of humanity has decreed rewards and punishments as one of the motives to impel men to even their noblest endeavours, the inexact distribution of these motives will give rise to that contradiction, as little noticed as it is of common occurrence, namely, that the laws punish crimes which are entirely of their own creation. If an equal penalty is attached to two crimes of unequal injury to society, the greater crime of the two, if it promise a greater advantage than the other, will have no stronger motive in restraint of its perpetration.[197] Whoever, for example, sees the same punishment of death decreed for the man who kills a pheasant and the man who slays his fellow or falsifies an important document, will draw no distinction between such crimes; and thus moral sentiments, the product only of many ages and of much bloodshed, the slowest and most difficult attainment of the human mind, dependent, it has been thought, on the aid of the most sublime motives and on a parade of the gravest formalities, will be destroyed and lost.