Valuables fall naturally and exactly into three classes, Commodities, Services, and Credits. The reasons are obvious at first glance, why articles falling in the first class occupied the thoughts and the efforts of men almost exclusively for the first thousand years of recorded history. Commodities appealed to the senses of men: they are visible, tangible, weighable. Some form of personal slavery existed everywhere, and largely withdrew attention from personal services bought and sold; and there was not apparently sufficient personal confidence between man and man in the earlier ages to allow much development of credits, whose ground is personal trust and whose sphere is future time. Commodities, on the other hand, fitted by the efforts of some men to satisfy the immediate wants of other men, all ready for delivery, to be exchanged against other commodities similarly fitted and at hand, took the field apparently in the earliest ages of recorded Time, gradually became very large in volume, opened new routes of travel and transportation, and served to connect in a rough and ready way neighboring tribes and even neighboring nations. _Commodities are the class of Valuables comprising material things, organic and inorganic, fitted by human efforts to satisfy human desires._ Cattle were probably among the first things to become valuable, that is, salable; and it is certain, that they became very early in many quarters of the world a sort of Money or standard of comparison among other things exchangeable, and indeed they continue to be such in some quarters to this day. Near the middle of the sixth book of the Iliad occur these lines:-- "Then did the son of Saturn take away The judging mind of Glaucus, when he gave His arms of gold away for arms of brass Worn by Tydides Diomed,--_the worth Of fivescore oxen for the worth of nine_." Gold and silver also became valuable in the ordinary way in very early times, and later became Money or a medium in exchanging other things; and much later other metals came into use as commodities and then too as money; for the Latin word for money, _pecunia_, derived from _pecus_, cattle, seems to imply some original equivalence in value between the bronze stamped with the image of cattle and the cattle themselves. Parcels of land subdued and improved by human hands were probably bought and sold in some portions of the world as early as anything was,--at any rate very early. Land-parcels are a commodity under the definition. Another passage from Homer, towards the end of the seventh book of the Iliad, displays some of the commodities in common use during the heroic age in Greece:-- "But the long-haired Greeks Bought for themselves their wines; some gave their brass, And others shining steel; some bought with hides, And some with steers, and some with slaves, and thus Prepared an ample banquet."