Unless we justify wars of extermination, war has no biological sanction, and Christianity is not flying in the face of nature by condemning it. On the contrary, by condemning every form of parasitism, it indicates the true path of evolution. It is equally right in rejecting the purely economic valuation of human goods. The ‘economic man’ does not exist in nature; he is a fictitious creature who is responsible for a great deal of social injustice. Some modern economists, like Mr. Hobson, would substitute for the old monetary standards of production and distribution an attempt to estimate the ‘human costs’ of labour. Creative work involving ingenuity and artistic qualities is not ‘costly’ at all, unless the hours of labour, or the nervous strain, exceed the powers of the worker. More monotonous work is not costly to the worker if the day’s labour is fairly short, or if some variety can be introduced. The human cost is greatly increased if the worker thinks that his labour is useless, or that it will only benefit those who do not deserve the enjoyment of its fruits. Work which only produces frivolous luxuries is and ought to be unwelcome to the producer, even if he is well paid. It must also be emphasised that worry and anxiety take the heart out of a man more than anything else. Security of employment greatly reduces the ‘human cost’ of labour. These considerations are comparatively new in political economy. They change it from a highly abstract science into a study of the conditions of human welfare as affected by social organisation. The change is a victory for the ideas of Buskin and Morris, though not necessarily for the practical remedies for social maladjustments which they propounded. It brings political economy into close relations with ethics and religion, and should induce economists to consider carefully the contribution which Christianity makes to the solution of the whole problem. For Christianity has its remedy to propose, and it is a solution of the problem of war, not less than of industrial evils.