This round-about Barter, I cannot too often repeat, does not change in the least degree the primary notions explained in the preceding chapters. When the evolution is complete, each of those who have had part in it presents still the triple phenomenon, ‹want›, ‹effort›, ‹satisfaction›. We have but to add, the exchange of efforts, the transmission of services, the separation of employments, with all their resulting advantages—advantages to which every one of the parties has contributed, seeing that isolated individual labour is a ‹pis aller›, always reserved, and which is only renounced in consideration of a certain advantage. It is easy to comprehend that Barter in kind, especially the indirect and round-about barter which I have described, cannot be much extended, and it is unnecessary to dwell upon the obstacles which set limits to it. How could he manage, for example, who wished to exchange his house against the thousand articles which enter into his annual consumption? In any case, Barter could never take place but among the few persons who happen to be acquainted with each other. Progress and the Division of Labour would soon reach their limits if mankind had not discovered the means of facilitating exchanges. This is the reason why men, from the earliest ages of society, have employed an intermediate commodity to effect their transactions—corn, wine, animals, and almost always, the precious metals. Such commodities perform this function of facilitating exchanges more or less conveniently; still any one of them can perform it, provided that, in the transaction, Effort is represented by ‹value›, the transmission of which is the thing to be effected. When recourse is had to an intermediate commodity, two economic phenomena make their appearance, which we denominate ‹Sale› and ‹Purchase›. It is evident that the idea of ‹sale› and ‹purchase› is not included in direct Barter, or even in round-about Barter. When a man gives another something to drink, in consideration of receiving from him something to eat, we have a [p110] simple fact which we cannot analyze farther. Now, what we must remark in the very outset of the science is, that exchanges which are effected by means of an intermediate commodity do not lose the nature, the essence, the quality of barter—only the barter is no longer simple, but compound. To borrow the very judicious and profound observation of J. B. Say, it is a barter of ‹two factors› [troc à deux facteurs], of which the one is called ‹sale› and the other ‹purchase›—factors whose union is indispensable in order to constitute a complete barter.