be prevented by the anger of their victims. Such injustices ought, as far as possible, to be prevented by the State.
The most obvious example of a matter where the general welfare depends upon a universal minimum is sanitation and the prevention of infectious diseases. A single case of plague, if it is neglected, may cause disaster to a whole community. No one can reasonably maintain, on general grounds of liberty, that a man suffering from plague ought to be left free to spread infection far and wide. Exactly similar considerations apply to drainage, notification of fevers, and kindred matters. The interference with liberty remains an evil, but in some cases it is clearly a smaller evil than the spread of disease which liberty would produce. The stamping out of malaria and yellow fever by destroying mosquitoes is perhaps the most striking example of the good which can be done in this way. But when the good is small or doubtful, and the interference with liberty is great, it becomes better to endure a certain amount of preventable disease rather than suffer a scientific tyranny.
Compulsory education comes under the same head as sanitation. The existence of ignorant
