worlds impossible. As another example, when wealth is transferred during marriage, divorce, inheritance, and other crucial life events, or during the collection of taxes or tribute, it is improbable that this event will coincide with the recipient's desire for the commodities the payer can readily obtain. All of these transactions entail an improbable coincidence of wants and events which can be resolved by the existence of a monetary medium. See also Want References W.S. Jevons (1875), Money and the Mechanism of Exchange, Chapter 1, paragraphs 5-6. London: Macmillan. Carl Menger, "On the Origin of Money" Nobuhiro Kiyotaki and Randall Wright (1989), 'On money as a medium of exchange', "Journal of Political Economy" 97, pp. 927–54. Monetary economics