We have already stated, in the Seventh[844] Book, who were the first discoverers of gold, as well as nearly all the other metals. The highest rank has been accorded to this substance, not, in my opinion, for its colour, (which in silver is clearer[845] and more like the light of day, for which reason silver is preferred for our military ensigns, its brightness being seen at a greater distance); and those persons are manifestly in error who think that it is the resemblance of its colour to the stars[846] that is so prized in gold, seeing that the various gems[847] and other things of the same tint, are in no such particular request. Nor yet is it for its weight or malleability[848] that gold has been preferred to other metals, it being inferior in both these respects to lead—but it is because gold is the only[849] substance in nature that suffers[850] no loss from the action of fire, and passes unscathed through conflagrations and the flames of the funeral pile. Nay, even more than this, the oftener gold is subjected to the action of fire, the more refined in quality it becomes; indeed, fire is one test of its goodness, as, when submitted to intense heat, gold ought to assume a similar colour, and turn red and igneous in appearance; a mode of testing which is known as “obrussa.”[851] The first great proof, however, of the goodness of gold, is its melting with the greatest difficulty: in addition to which, it is a fact truly marvellous, that though proof against the most intense fire, if made with wood charcoal, it will melt with the greatest readiness upon a fire made with chaff;[852] and that, for the purpose of purifying it, it is fused with lead.[853] There is another reason too, which still more tends to enhance its value, the fact that it wears the least of all metals by continual use: whereas with silver, copper, and lead, lines may be traced,[854] and the hands become soiled with the substance that comes from off them. Nor is there any material more malleable than this, none that admits of a more extended division, seeing that a single ounce of it admits of being beaten out into seven hundred and fifty[855] leaves, or more, four fingers in length by the same in breadth. The thickest kind of gold-leaf is known as “leaf of Præneste,” it still retaining that name from the excellence of the gilding upon the statue of Fortune[856] there. The next in thickness is known as the “quæstorian leaf.” In Spain, small pieces of gold are known by the name of “striges.”[857]