This book, first published in 1973, takes up an important approach to capital which had gone out of fashion. There has been some recent renewed interest in this approach. The ‘Austrian’ theory of capital concentrates on the inputs and outputs in the productive process, and has an advantage over more modern theories of economic dynamics in that it is more naturally expressible in economic terms: the production process over time is taken as a whole, rather than disintegrated. However, this approach had been largely abandoned because it seemed to be unable to deal with fixed capital. The book overcomes this problem here by allowing for a sequence of outputs, and the consequences for dynamic economics are profound and novel.