and silver. Value is based on utility, but utility is not intrinsic in any substance; and a thing is only useful so far as it is supplied in needful quantities at the right time, the degree of utility constantly varying. And so, although we may get the value of x (gold and silver) in terms of y (other commodities), and the value of y in terms of x, both x and y remain unknown and variable quantities, however glibly we may talk about them.
Although the same difficulty confronts us here that is met in all attempts at the ultimate analysis of things, none the less is it imperative that there should be a fixity of standards, rigidly adhered to. To define a pound avoirdupois is as difficult as to define a pound sterling; but commerce and science are alike dependent upon absolute adherence to certain standards of weight, and upon the assumption that the law of gravitation, by which weight is determined, is inflexible.
Until the indestructibility of matter and the persistence of force were demonstrated, there was nothing absurd in the supposition that matter could be created and annihilated, force produced and destroyed; and men of genius and learning vainly sought to turn dross to gold, to find the elixir of life, to construct machines which should create their own force. Modern chemistry has dispelled the dreams of the alchemist; physiology has determined the laws of waste and supply and fixed pretty definitely the limitations of life; and the discoveries of Meyer and Joule have shown the fallacy of perpetual motion. These things are now pretty generally understood, although a lunatic is still occasionally to be found who wastes his life because of his inability to comprehend them: but it is not so generally recognized that the principle of the correlation of forces is universal; that it applies rigidly to all human activities; and that it is quite as impossible in economical dynamics as elsewhere to get something for nothing.
That coins are simply stamped bullion, and that the purchasing power of money is regulated by the quantity of pure metal only is now conceded by all economic writers; but the establishment of this principle is comparatively recent. In early times most extraordinary delusions prevailed on this subject, nor are they yet wholly dissipated. It will be interesting and instructive to note some of the mutations which have been caused in the world's coinage by the numerous royal and legislative attempts to make a part equal to the whole.
The coins of all countries seem to have been called by the same name as the weights used in them, and to have originally contained the quantity of metal indicated by their names. The coins used in Greece, Italy, France, and England, weighed in the first instance just a talent, an as, or pond, a livre, or a pound.
The Roman as, or libra, at first contained twelve ounces of copper, and was divided into twelve parts or unciæ, a division which was maintained for a long time. It is not known who first falsified the certifi-
