The concurring operation of these causes produced, in the three last centuries of the Roman empire, a very great scarcity in the supply of the precious metals for the purposes of the public currency, and consequently a most distressing fall in prices, and diminution in the remuneration of industry, accompanied by a proportional increase in the weight of debt and taxes. And the progressive effect of these changes appeared in the clearest manner, in the repeated changes which were made by successive emperors in the value of the gold and silver coins which passed current in the empire. Gold became progressively so scarce in proportion to silver, that the proportion between the two, which at first had been 1 to 10 in the time of Augustus, rose in time to 1 to 12-1/2, and was fixed by Constantine the Great at 1 to 14-2/5ths.[67] In consequence of this rise in the value of gold--the precise counterpart of what was experienced in Great Britain in the later years of the war, when a _light_ guinea sold for 25s.--the quantity of gold in the _aureus_, or chief gold Roman coin, was progressively diminished, till it came to contain little more than _half_ its former weight of that precious metal. The learned Greaves has shown, after diligent inquiry, that while in the time of the Antonines the _aureus_ weighed 118, in the time of Majorian, in the fifth century, it had come to weigh only 68 grains.[68] This is a clear indication, that 68 grains of gold were now equal in value to what 118 grains had been three centuries before; for Majorian, by a special decree, ordered all _aurei_ of whatever reign, the Gallic _solidus_ alone excepted, to pass, not according to weight but standard.[69] That is the most decisive proof to what a grievous extent the currency had, from the operation of the causes which have been mentioned, come to be contracted; for as gold constitutes, from its superior value, at least nine-tenths of the circulating medium of every civilized state, so great a rise in its value could only have been occasioned by a very great contraction of the whole currency. We know in what state the metallic currency of Great Britain was when the _light_ guinea was selling for twenty-five shillings.