Commodity market in Sumer between 4500 BC and 4000 BC. Sumerians first used clay tokens sealed in a clay vessel, then clay writing tablets to represent the amount—for example, the number of goats, to be delivered. These promises of time and date of delivery resemble futures contract. Early civilizations variously used pigs, rare seashells, or other items as commodity money. Since that time traders have sought ways to simplify and standardize trade contracts. Gold and silver markets evolved in classical civilizations. At first the precious metals were valued for their beauty and intrinsic worth and were associated with royalty. In time, they
Commodity be longer than the time spent on the same commodity by a skilled worker. Thus, under this analysis, the commodity produced by an unskilled worker would be more valuable than the same commodity produced by the skilled worker. Marx pointed out, however, that in society at large, an average amount of time that was necessary to produce the commodity would arise. This average time necessary to produce the commodity Marx called the "socially necessary labour time" Socially necessary labour time was the proper basis on which to base the "exchange value" of a given commodity. Value and price are not