_The Intermediate Type of Exchanges and the Final One._--In the next stage a man becomes wholly a specialist, making one kind of product only and bartering it away for others. It might seem, at the first glance, that differentiation has now done its full work; but it is very far from having done so. Making one complete good for consumption is still a complex operation, which can advantageously be subdivided in such a way that one man produces a raw material while another works it up into a useful shape. A gain may be made by a further division of the manufacturing process, whereby the first worker makes only the rawest material, another fashions it somewhat, a third carries the process farther, and a fourth or a still later one completes it. In modern industry the material must often pass through very many hands before it is ready to be made over to the consumer. Each man in the series puts a touch on it and passes it on to his successor. A''' A'' A' A A''' is an article of consumers' wealth and A is the rawest material that enters into it. A' is this material somewhat transformed; A'' is the same material after it has received the second transformation and needs only a final touch to convert it into A''', in which state it will be ready for the consumer's use. We have here a symbol of what is actually taking place in the industry of the world. Cattle are grazing on western ranches; hides are tanning in the woods of Pennsylvania; leather is going through the many changes that fashion it into shoes in the mills of Brockton; shoes are arranged on the shelves of retailers in New York in readiness for the people who are to wear them. These are stages in the making of a single product, and a thousand different products are coming into existence in a like way. _A Representation of the Groups, or Specific Industries, which compose Economic Society._--If we put beside the series of A's a series of B's and one of C's, we have a much simplified representation of what is actually taking place. There are, in reality, a myriad of different things which almost every consumer uses, and every one of them is made by a series of productive operations like the one we have described. The very fact that there are so many of them that it is hopeless to try to represent them all in the table makes it desirable to illustrate the principle by tabulating only a few and to assume that these few are all that there are. For the purposes that we have in mind it is entirely safe to suppose that a series of A's, one of B's, and one of C's represent all the consumers' goods that society uses. What we wish to ascertain is how the different series work together to furnish an income for each member of society.