FOREIGN AUTHORS QUOTED.—Juba,[639] Andreas,[640] Salpe,[641] Apion,[642] Pelops,[643] Apelles,[644] Thrasyllus,[645] Nicander.[646] BOOK XXXIII. THE NATURAL HISTORY OF METALS.[647] CHAP. 1. (1.)—METALS. We are now about to speak of metals, of actual wealth,[648] the standard of comparative value, objects for which we diligently search, within the earth, in numerous ways. In one place, for instance, we undermine it for the purpose of obtaining riches, to supply the exigencies of life, searching for either gold or silver, electrum[649] or copper.[650] In another place, to satisfy the requirements of luxury, our researches extend to gems and pigments, with which to adorn our fingers[651] and the walls of our houses: while in a third place, we gratify our rash propensities by a search for iron, which, amid wars and carnage, is deemed more acceptable even than gold. We trace out all the veins of the earth, and yet, living upon it, undermined as it is beneath our feet, are astonished that it should occasionally cleave asunder or tremble: as though, forsooth, these signs could be any other than expressions of the indignation felt by our sacred parent! We penetrate into her entrails, and seek for treasures in the abodes even of the Manes,[652] as though each spot we tread upon were not sufficiently bounteous and fertile for us! And yet, amid all this, we are far from making remedies the object of our researches: and how few in thus delving into the earth have in view the promotion of medicinal knowledge! For it is upon her surface, in fact, that she has presented us with these substances, equally with the cereals, bounteous and ever ready, as she is, in supplying us with all things for our benefit! It is what is concealed from our view, what is sunk far beneath her surface, objects, in fact, of no rapid formation,[653] that urge us to our ruin, that send us to the very depths of hell. As the mind ranges in vague speculation, let us only consider, proceeding through all ages, as these operations are, when will be the end of thus exhausting the earth, and to what point will avarice finally penetrate! How innocent, how happy, how truly delightful even would life be, if we were to desire nothing but what is to be found upon the face of the earth; in a word, nothing but what is provided ready to our hands! CHAP. 2.—GOLD. Gold is dug out of the earth, and, in close proximity to it, chrysocolla,[654] a substance which, that it may appear all the more precious, still retains the name[655] which it has borrowed from gold.[656] It was not enough for us to have discovered one bane for the human race, but we must set a value too upon the very humours of gold.[657] While avarice, too, was on the search for silver, it congratulated itself upon the discovery of minium,[658] and devised a use to be made of this red earth.