Metallurgy and agriculture were the two arts which produced this great revolution. The poets tell us it was gold and silver, but, for the philosophers, it was iron and corn, which first civilised men, and ruined humanity. Thus both were unknown to the savages of America, who for that reason are still savage; the other nations also seem to have continued in a state of barbarism while they practised only one of these arts. One of the best reasons, perhaps, why Europe has been, if not longer, at least more constantly and highly civilised than the rest of the world, is that it is at once the most abundant in iron and the most fertile in corn. It is difficult to conjecture how men first came to know and use iron; for it is impossible to suppose they would of themselves think of digging the ore out of the mine, and preparing it for smelting, before they knew what would be the result. On the other hand, we have the less reason to suppose this discovery the effect of any accidental fire, as mines are only formed in barren places, bare of trees and plants; so that it looks as if nature had taken pains to keep the fatal secret from us. There remains, therefore, only the extraordinary accident of some volcano which, by ejecting metallic substances already in fusion, suggested to the spectators the idea of imitating the natural operation. And we must further conceive them as possessed of uncommon courage and foresight, to undertake so laborious a work, with so distant a prospect of drawing advantage from it; yet these qualities are united only in minds more advanced than we can suppose those of these first discoverers to have been. With regard to agriculture, the principles of it were known long before they were put in practice; and it is indeed hardly possible that men, constantly employed in drawing their subsistence from plants and trees, should not readily acquire a knowledge of the means made use of by nature for the propagation of vegetables. It was in all probability very fang, however, before their industry took that turn, either because trees, which together with hunting and fishing afforded them food, did not require their attention; or because they were ignorant of the use of corn, or without instruments to cultivate it; or because they lacked foresight to future needs; or lastly, because they were without means of preventing others from robbing them of the fruit of their labour.