But if the custody of the criminal class has been overrated as a preventive of crime, or regarded as the sole preventive instead of one amongst many, it does not follow that crime on that account must be left to itself. It only follows that we should trust to punishment less and to other agencies more in our war with[104] crime, and that we should seek to check the latter at its source, not in its full stream, by attending to the improvement of the general conditions of life. It is quite certain, for instance, that the spread of education, of which Beccaria wrote in terms of such despair, means the diminution of crime; and as the majority of crimes are committed between the ages of twenty and forty, it may be predicted that from the present year onwards the great Act of 1870 will bear increasing fruit in lowering our criminal statistics. More too may be hoped for from the electric light than from any multiplication of prisons. Not only is it the general interest that crimes should not be committed, but that they should be rare in proportion to the evils they cause to society. The more opposed therefore that crimes are to the public welfare, and the more numerous the incentives to them, the stronger should be the repellent obstacles. This principle accordingly establishes the necessity of a certain proportion between crimes and punishments.