My reluctance to undertake this work would have been even greater if from the beginning I had been aware of the magnitude of the task that awaited me. As at first contemplated, this study was intended as little more than a systematic exposition of what I imagined to be a fairly complete body of doctrine which, in the course of years, had evolved from the foundations laid by Jevons, Böhm-Bawerk, and Wicksell. I had little idea that this task of systematisation would uncover serious gaps in the reasoning which had yet to be bridged, and that some of the simplifications employed by the earlier writers had such far-reaching consequences as to make their conceptual tools almost useless in the analysis of more complicated situations. The most important of these inappropriate simplifications, of the dangers of which I became aware at a comparatively early stage, was the attempt to introduce the time factor into the theory of capital in the form of one single relevant time interval â€” the “average period of production.” But it gradually became clear that this supposed simplification evaded so many essential problems that the attempt to replace it by a more adequate treatment of the time factor raised a host of new questions which had never been really considered and to which answers had to be found.
Source link: http://archive.mises.org/5939/the-pure-theory-of-capital-by-f-a-hayek/