All this, however, reads like a lawyer's brief about a simple matter. The greater the volume of goods and services resulting from the labor of society, the more there is to share out; and the greater in amount will the share of the wage earners be, even if their relative share is not increased.[13] The volume of production depends upon the quantity and quality of each and every agent that assists in production, and upon the organization of the separate powers, and above all upon the progress of invention and of the industrial arts. It depends directly upon: first, the natural resources of the country--which are ordinarily summarized in economic discussion under the term "land"--"by land is meant the material and the forces which nature gives freely for man's aid, in land and water, in air and light and heat;"[14] second, the "accumulated provision for the production of material goods"--capital--which was discussed in the preceding chapter; thirdly, on the labor of men and women--on the degree of spirit, skill, energy and intelligence which characterizes that labor; fourthly, on the quality of leadership which manifests itself in industrial affairs, and the success with which the elements of production are brought into well directed cooperation; fifthly, on the progress of invention and the industrial arts. The relationship between the volume of production and wages is indirect. Though it is true that the larger the product, the higher wages will be, all other forces remaining the same, the connection between them is by no means simple or direct. That is because the wage earners share in a product to the making of which other agents contribute. In our present industrial system work is done under direction, and by the aid of tools and machinery; it is highly subdivided. It is impossible to determine the contribution to total production of any group of workmen, or of all workmen. The product is a joint result in which the part played by any one group, instrument, or factor of production cannot be traced. Who, for example, is able to say how much productive activities have been aided by the invention of the telephone and the growth of the telephone system? The problem of the distribution of the product of modern industry is so difficult and so much to the fore because so many different people contribute in some way or other to the product and have a claim upon it.