With the mental, as well as with the bodily, states of fellow-citizens, his enjoyments are in multitudinous ways bound up. Stupidity like weakness raises the cost of commodities. Where farming is unimproved, the prices of food are higher than they would else be; where antiquated routine maintains itself in trade, the needless expense of distribution weighs on all; where there is no inventiveness, every one loses the benefits which improved appliances diffuse. Other than economic evils come from the average unintelligence--periodically through the manias and panics that arise because traders rush in herds all to buy or all to sell; and habitually through the mal-administration of justice, which people and rulers alike disregard while pursuing this or that legislative will-o'-the-wisp. Closer and clearer is the dependence of his personal satisfactions on others' mental states, which each experiences in his household. Unpunctuality and want of system are perpetual sources of annoyance. The unskillfulness of the cook causes frequent vexation and occasional indigestion. Lack of forethought in the housemaid leads to a fall over a bucket in a dark passage. And inattention to a message or forgetfulness in delivering it, entails failure in an important engagement. Each, therefore, benefits egoistically by such altruism as aids in raising the average intelligence. I do not mean such altruism as taxes ratepayers that children's minds may be filled with dates, and names, and gossip about kings, and narratives of battles, and other useless information, no amount of which will make them capable workers or good citizens; but I mean such altruism as helps to spread a knowledge of the nature of things and to cultivate the power of applying that knowledge.