First: there are matters in which the welfare of the whole community depends upon the practically universal attainment of a certain minimum; in such cases the State has the right to insist upon this minimum being attained. Secondly: there are ways in which, by insisting upon the maintenance of law, the State, if it does nothing further, renders possible various forms of injustice which would otherwise 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 masses in a population is a danger to the community; when a considerable percentage are illiterate, the whole machinery of government has to take account of the fact. Democracy in its modern form would be quite impossible in a nation where many men cannot read. But in this case there is not the same need of absolute universality as in the case of sanitary measures. The gipsies, whose mode of life has been rendered almost impossible by the education authorities, might well have been allowed to remain a picturesque exception. But apart from such rather unimportant exceptions, the argument for compulsory education is irresistible. What the State does for the care of children at present is less than what ought to be done, not more. Children are not capable of looking after their own interests, and parental responsibility is in many ways inadequate. It is clear that the State alone can insist upon the children being provided with the minimum of knowledge and health which, for the time being, satisfies the conscience of the community. The encouragement of scientific research is another matter which comes rightly within the powers of the State, because the benefits of discoveries accrue to the community, while the investigations are expensive and never individually certain of achieving any result. In this matter, Great Britain lags behind all other civilized countries.