By economy (_Wirthschaft_=husbandry or housekeeping), we mean the systematized activity of man, to satisfy his need (_Bedarf_=requisite) of external goods.(61) This treatise is concerned only with economic goods (ends or means of economy).(62) The greater the advance of civilization or human culture, the less apt are men to pursue the satisfaction of their wants, isolated from their fellows, or, in other words, to carry on their economies or husbandries apart from one another. The more numerous the wants of men, and the more different in kind their faculties are, the more natural does exchange(63) become. Since all goods derive their character as goods from the fact that they are destined to satisfy human wants, the very possibility of exchange must greatly increase the possibility of things to become goods. Think of the machinist, whose products are used only by the astronomer, while the latter is never in a way to manufacture them for himself. (_Hufeland._) Commerce is the series of combinations, created by the interchange of services: “a living net of relations, which wants and services are ever weaving and unweaving.” (_Hermann._) As a rule, with an advance in civilization, there is an increase in the number of goods, which become economic goods, and in the number of economic goods which become commercial goods (objects or means promotive of commerce).(64) But this is to be considered a real advancement only to the extent that that which is obtained is superior to that which was possessed before, in consequence of the specialization of callings or the greater division of labor (§ 48 ff.). When a little street Arab exacts money from a stranger for pointing out the way, we rightly censure him; but no one would find it improper if he should first fit himself to play the part of a guide, and then live by his calling.(65) Section III. Goods.—The Three Classes Of Goods. All economic goods are divided into three classes: A. _Persons or personal services._ It is entirely repugnant to the feeling of humanity to regard a man’s person in its entirety as an instrument intended to satisfy the wants of another.(66) Yet this happens wherever slavery exists; in its coarsest form, in cannibalism. Among civilized nations, we can speak, under this head, only of individual services or capabilities of persons; or, indeed, of the aggregate of the services rendered by them during a time determined at pleasure, or a short time.(67) B. _Things_, both moveable and immovable.(68)