There are three kinds of things only ever bought and sold in this good world of ours. In the preceding chapter we have conned carefully the first kind, material commodities, in their three subdivisions of land-parcels and products of such parcels and products of free land and sea. In the present chapter we come to study the second kind of valuable things, personal services, which we shall also find subdivisible into three classes. We have treated of Commodities first, because their value in its grounds and changes is more easily understood than that of the other two kinds, while in point of _time_ Services might well enough have been considered first, since it is these that manipulate into value the originally rude forms of Nature. The main difference between the two is this: in Commodities the attention is naturally drawn to tangible _things_ offered for sale, such as lands and wheat and fish; while in Services the attention is strongly drawn to _persons_ offering them for sale, such as the common laborer and the skilled artisan and the professional artist. This distinction, though obvious and useful as between commodities and services, is not after all radical; because Economics is a science of Persons from beginning to end; inasmuch as the services precede and are merged in the commodities, and inasmuch as the Desires (personal) of some men for the renderings of other men antedate and underlie all exchanges whatsoever. Personal Services are technically named _Labor_ in the science of Political Economy. This nomenclature is old and familiar, and will probably always persist on that account, but it is not of itself of the happiest, and it gives birth to some ambiguities and many fallacies. Let us look at these for a moment, before we pass to the definition and discussion of what is commonly called Labor, but what is better described by the term, Personal Services.