In the present day, the discovery and the working these new metallic stratifications are the only causes which can materially change the relative value of the precious metals. Formerly, conquest, by which one nation became rich at the expense of another, or the pillage of those great reservoirs of money called public treasures, throwing suddenly vast sums of money into circulation, could not fail to depreciate either one or other, if not both, of the precious metals. It was thus that the conquests of Alexander, opening the gates of the East, inundated the Greek world with the precious metals, which were lowered in value by their abundance, and dissipated from their very excess. After the capture of Syracuse by the Romans, silver, the foundation of the treasure they had seized, fell suddenly in price, so that seventeen pounds of silver were valued at one of gold. A little later the relative price was as 12 to 1, when Cæsar, having plundered the two milliards contained in the public chest, so reduced the value of gold, which then predominated, that the proportion fell to 9 to 1. Under the Roman Emperors, the production of gold began to slacken,--the progress of mechanical science, on the other hand, gave a constant impetus to the working of the silver mines of Asia, Thrace, and Spain. The comparative value of the two metals again changed; it was as 18 to 1 in the time of Theodosius the Younger, 412 years after the birth of Christ. At the commencement of the fall of the Roman Empire, in the 4th century, the value of the precious metals approached that of our own days. The invasion of the barbarians, in dispersing and dissipating the accumulated treasures of the West, destroyed for a time the industry required for their renewal. Money, on account of its scarceness, acquired an extraordinary power; the price of every article fell, or, in other words, the value of silver rose to a most extraordinary degree. Not only did the value of money and of the precious metals increase in that long dark night of the middle ages, but the relative value between silver and gold, which had been established by the progress of industry, again changed. The value of gold, in relation to other commodities, was preserved longer than that of silver, owing to its greater general value, and to its being the less destructible metal; and also because its supply was fed by the washings of the golden sands; a fit occupation for the knowledge and tastes of an ignorant people. The working of the silver mines, on the other hand, being a work befitting a civilized and scientific people, was naturally interrupted, and languished during a period of spoliation and endless warfare. Hence, as we may suppose, arose the scarcity, both relative and absolute, of silver; the comparison with gold remained at 11 and 12 to 1 from the 9th to the middle of the 16th century. It required the excessive and sudden abundance, springing from the working of the