There has been a marked revival of classical economic theory since the 1960s. This was associated partly with Sraffa's contribution, partly also with the development of post-Keynesian economics. It has given rise to a series of ongoing controversies. This collection of essays, some previously published, some new, starts with a survey of the present state of the debate. Several papers are concerned with the new classical solution to the problem of value and choice of technique in the presence of joint production. Fixed capital allows formalization of different kinds of technical progress which differ also in their macroeconomic effects. A novel contribution is made to capital theory: it is shown how intertemporal equilibria are affected by technologies which exhibit reswitching through changed stability conditions. Further essays deal with the composition of output and effective demand and the relation between Keynesian and classical theories and environmental economics.