As structural Marxists, Althusser and Balibar were concerned to understand how "the problems of diachrony " in the transition from one mode of production to another could be related to the overall structure or "synchrony" of production. In Reading Capital (1970), they argue, in similar vein to Bloch, that the succession of different modes of production as theorized by Marx is not a teleological process driven by "the forward march of the productive forces", but that instead periods of transition are marked by "the coexistence of several modes of production":