Money is exclusively of use to those who enter into commercial transactions. Thus a man who could sufficiently provide for himself in everything without any such transactions, would not have to make any use of money; a landed proprietor may have a considerable fortune and have only a small monetary need, whilst a merchant whose fortune may be much less will find himself in a very different situation: for the greater part of his fortune consisting of merchandise, continually renewed, and consequently engaged in circulation, his monetary need will be considerable. It may therefore be said that the need of money is proportional to the need for commercial transactions. Beyond what we have just pointed out, has money fulfilled, or does it fulfil any other purpose? We shall see. If, from the beginning, we could have had a system allowing us to exactly register transactions, would money have been indispensably necessary? In a word, is money in point of fact the particular element in such transactions which caused the writing of them down, or, in reality does not its use hide an agency entirely independent of money? Let us examine this. But we cannot do so without offering as a necessary preliminary a few words in explanation of the term «transactions», which we have already used and which will continue to be employed in this paper to the exclusion of the word «exchanges». In our opinion exchange properly speaking,--true exchange and free from the alloy of any foreign element whatsoever, has never been anything but barter; and as soon as the system of barter was left and that of money entered upon, the exchange system was rather abandoned for another system quite different, than that one form of exchange was simply substituted for another form of exchange. And if we have continued afterwards to make use of the word «exchange» it is due more to the force of habit than in order to define the actual condition of things. What in reality fundamentally characterises barter, is that it is an exchange, carried out on the spot, of goods immediately usable by the two parties, each of them giving one usable thing in order to enter into possession of another; whilst that which fundamentally characterises the operation of selling and buying, by means of money, is that it constitutes an exchange of goods carried out on the spot, of which one form only can be immediately used by one of the parties, the other party obtaining not a real thing but an instrument by which he will be able to procure it. So that the party who has received the money, the seller, has only thus obtained a _power_ to make subsequently an inverse operation, that is a purchase where and when it pleases him. The operation of selling and buying is then nothing less than the _exchange of a thing for a power_. But can we still make use of the word «exchange» to define such an operation? We do not think so, and it is for this reason that we substitute for it that of «transaction.»