Under a producers' society, the relation between the various groups of producers will be maintained through a system of book-keeping that will charge against each economic group what it uses in the form of raw materials, machinery and the like, and will credit each group with the value of its product. Such a system is in vogue in any large industrial plant, where each department keeps its own accounts, charges the other departments with what they get from it and credits them with what they receive. The whole is handled through a central book-keeping system. The principle of social book-keeping is not new, therefore, but is an essential link in any large and complex economic organization. It merely remains to apply the principle to producers' groups instead of to the affairs of a private banker or to the book-keeping system of some great industrial trust. How shall a joint control be exercised by all of the producers' groups over those economic activities, such as the handling of credit, or social book-keeping, that affect more than one of them? The obvious answer is that they can be transacted through some organization in which all of the groups participate on a footing of economic equality. Common, interests will sooner or later compel common action, or action through a joint board. The point has been reached in the economic history of the world where some such common action of the producing groups is vitally essential to their continued well-being. The logic of economic development is compelling men to turn from the owners' society of the present day to a producers' society, organized by the producing groups and functioning in those cases where the single group of producers finds effective function impossible. 4. _Federation as a Way Out_ Experience has shown that the best way to secure co-operation among a number of groups having more or less divergent interests is through a federated or federal system of organization, under which each of the constituent groups retains control over those matters which relate exclusively to the affairs of that group, while all matters affecting the well-being of two or more groups are handled through the central organization or federation.