a much less effective weapon for dealing with crime among Continental peoples, and in the United States, than it has shown itself to be in Great Britain; but this failure arises in the main from the laxity and indulgence with which criminals are treated in foreign prisons.  A prison to possess any reformative value must always be made an uncomfortable place to live in; Continental peoples and the people of America have to a large extent lost sight of this fact; hence the failure of their penal systems to stop the growth of the delinquent population.  If, however, imprisonment is not allowed to degenerate into mere detention, it is bound to act as a powerful deterrent upon grown-up offenders, and it is the only menace which will effectually keep many of them within the law.  The hope of reward and the fear of punishment, or, in other words, love of pleasure, and dread of pain, are the two most deeply seated instincts in the human breast; if Mr. Darwin’s theory be correct, it is through the operation of these fundamental instincts that such a being as man has come into existence at all.  In any case these instincts have hitherto been the chief ingredients of all human progress, the most effective spur to energy of all kinds, and when properly utilised they are the most potent of all deterrents to crime.  Were it possible for the hand of social justice to descend on every criminal with infallible certainty; were it universally true that no crime could possibly escape punishment, that every offence against society would inevitably and immediately be visited on the offender, the tendency to commit crime would probably become as rare as the tendency of an ordinary human being to thrust his hand into the fire.  The uncertainty of punishment is the great bulwark of crime, and crime has a marvellous knack of diminishing in proportion as this uncertainty decreases.  No amelioration of the material circumstances of the community can destroy all the causes of crime, and till moral progress has reached a height hitherto attained only by the elect of the race, one of the most efficient curbs upon the criminally disposed will consist in increasing the probability of punishment.

    [33] Cf. Tarde Philosophie Penale, p. 467.

In proportion as the probability of being punished is augmented, the severity of punishment can be safely diminished.  This is one of the paramount advantages to be derived from a highly efficient police system.  The barbarity of punishments in the Middle Ages is always attributed by historians to the barbarous ideas of those rude times.  But this is only partially true; one important consideration is overlooked.  In the Middle Ages it was extremely difficult to catch the criminal; in fact, it is only within the present century that an organised system for effecting the capture of criminals has come into existence.  The result of the nebulous police system of past times was that very few offenders were brought to justice