Although the sum total of human wants is incapable of being satisfied, each individual experiences daily the satisfaction of particular wants, in any one of which he can observe the law of diminishing utility. This law, stated briefly, is that as identical units of a good are consumed, the satisfaction derived from any unit is less than the satisfaction derived from the preceding one. By substituting the word "possessed" for the word "consumed" in the above definition the law may be made to apply to a stock of identical goods not actually in the process of consumption.