SUPPLY AND DEMAND 89 delicately adjusted economic system by the marginal cost of any normal business which was in a position of perfect equilibrium. In Chapter VII we shall meet again with the differentiation of business experience in the matter of business organisation and of the action of the law of equi-marginal returns in settling it ; and, since the analogies between the laws of demand and supply have been touched upon, it may further be remarked here that we shall find in Chapter IX that the marginal method discloses on the supply side of value a surplus analogous to that on the demand side known as consumer’s surplus. To conclude this chapter a few remarks may be made as regards the agents in production. Production consists in making utilities out of the material and forces at our disposal— utilities being defined as laid down in the previous chapter. The agents are commonly classified as land, labour, capital and organis ing. Land means not only land but all the forces of nature (apart from human nature) which are an aid to man’s productive activi ties, including animal life and winds and rivers and seas. Organising and labour are of the same general class, and to a large extent they interpenetrate one another, but for purposes