This weight in the form of a duck complete with incised feet which would have prevented undetected shaving of the weight (the equivalent of the milling of coins many centuries later) illustrates the development of measures.
One of the great unsolved problems in economics to this day is the emergence of markets and money and the appearance and role of a price system. A central question in political economy is the relationship between centralized control economies and a market economy with price formation. Babylon and Egypt are often used as examples of centralized states with prices dictated by a government price list. But this control in Babylon may have been more of an ideal than a fact. In modern times the Soviet Union attempted to operate with centralized prices, but this resulted in both misallocations in the economy and the growth of the black market (which is a manifestation of a non-legal flexible price system). Research into the history of Mesopotamia indicates many of the same problems as those encountered in the attempts to fix prices in modern times. The tablet shown is a merchant's balanced account giving prices of commodities bought and sold in the previous half year; these prices fluctuate considerably from each other as well as from the "dictated" prices known from later periods.