For a long time now the theory of capital has been under a cloud. Twenty years ago, when Professor Knight launched his attack on the capital theories of Boehm-Bawerk and Wicksell, there opened a controversy which continued for years on both sides of the Atlantic. Today very little is heard of all this. The centre of interest has shifted to other fields.In practice of course problems concerning capital have by no means lost their interest. There can be few economists who do not use the word ‘capital’ almost every day of their working lives. But apart from some notable exceptions, economists have ceased to ask fundamental questions about capital. It is pertinent to enquire why this has happened. It would seem that there are three major reasons to account for this curious neglect…. [From the text]