Group D are productive laborers, and their _own necessaries_ are productively consumed, but they are supplied by C, who keep themselves and D in existence. So long as C work, both C and D can go on producing. If D stopped working, they could be still subsisted as before by C; but A would be forced to produce for themselves. But, if C stopped working, D and C would be left without the necessaries of life, and would be obliged to cease their usual work. In this way it may be seen how much more important to the increase of material wealth C are than D, who labor “for the supply of unproductive consumption.” Of course, group D are desirable on other than economic grounds, because their labor represents what can be enjoyed beyond the necessities of life. Chapter III. Of Capital. § 1. Capital is Wealth Appropriated to Reproductive Employment. It has been seen in the preceding chapters that besides the primary and universal requisites of production, labor and natural agents, there is another requisite without which no productive operations beyond the rude and scanty beginnings of primitive industry are possible—namely, a stock, previously accumulated, of the products of former labor. This accumulated stock of the produce of labor is termed Capital. What capital does for production is, to afford the shelter, protection, tools, and materials which the work requires, and to feed and otherwise maintain the laborers during the process. These are the services which present labor requires from past, and from the produce of past, labor. Whatever things are destined for this use—destined to supply productive labor with these various prerequisites—are Capital.