"Professor Mises and Dr. Hayek have advanced theories which, though they fall into the general category of monetary explanations, yet seem altogether free from those deficiencies which have marked monetary explanations in general. They explain the effects of fluctuations in the supply of money not so much in terms of fluctuations of the general price level as in terms of fluctuations of relative prices and the consequent effects on what may be called the ‘time-structure’ of production."