This volume, by two eminent monetarist economists, offers a unique perspective on a key issue of monetary economics: the effect of money on output. Karl Brunner and Allan Meltzer address the theoretical aspects of this issue with the purpose of understanding their policy implications. They offer an historical overview of the relationship between money and output, and then go on to present a model of a monetary economy before examining the real sector. The theme of the final lecture is uncertainty and the costs of acquiring information.