There is one aspect of recent developments in economic thought and discussion in the U.S.S.R. that perhaps deserves more emphasis than it has received: the degree of interconnection between several apparently distinct discussions which have been going on for a number of years, and the extent to which these discussions have had their roots in actual problems arising in the Soviet economy. For long it was evidently discouraged by the prevailing view that Marxist political economy, since it was essentially a study of the ‘social relations of production’, was concerned only with the qualitative aspect of social phenomena. Attention to the quantitative aspect of economic relations was apt accordingly to be frowned upon as ‘formalism’. As the process of investment continues, the accumulation of capital and the technical equipment of industry develop, and in this respect the situation in the economy at large changes, just as it does in a particular industry such as coal.