This formula shows that the value of things is only relatively to be taken for it varies ceaselessly, shifting to as great a degree as supply and demand itself, just as human desire often does,--it is only mathematically fixed in time and space, we would again repeat for an infinitely short period. This being so it is evident that it becomes possible to put down in writing all transactions by means of the unity determined on. And if this writing down of transactions can be made under a legal form, that is, can be carried out under conditions which have the effect of conferring on the seller a _legal right_, corresponding to what the thing is worth to him who acquires it, and here we enter into the conception of «social accountancy», it becomes useless, superfluous and even harmful to make a material use of the thing representing the unity of the value adopted. It is thus that from the beginning, from the very time barter is abandoned and it is no longer necessary to give a kilogram of wheat to obtain possession of a thing, that at that very moment a writing down would confer on the holder of a thing a right representing a value equivalent to it and permitting him to effect under the same conditions new transactions. If things can thus take place, it will be seen how absurd it becomes to persist in the custom of representing materially a unity which should be detached from the support which has served to define it at a given moment, and which no longer appears as anything but an abstraction permitting in a homogenous manner the arithmetical representation by figures, of the value of things, relatively and individually. This abstract unity ought to be detached from every material tie. On the other hand, it becomes evident that money does not in the least constitute the indispensable element for effecting transactions. And if at the distant period to which the introduction of money goes back it had been possible to tell beforehand that transactions could be written down in a simple but legal manner, after having fixed as above indicated the numerical value of things by the use of a unity essentially invariable, an enormous error in principle would have been committed if to the unities admitted as estimates of value had been given, as is actually the case now, a representation of them in gold and silver,--the franc, the mark, the pound sterling. The usage of money has taken from the unity of value that character of invariability which it ought necessarily to possess. This unity being associated in point of fact with a real article of merchandise, society has been exposed either to want, or to have too much of the matter thus become the indispensable element of transactions, to suffer in fact monetary contractions and dilations, the results of the traffic which necessarily takes place, results which, for a nation producing the precious metals, like the United States does, may possibly end in disaster.