Mark Poster remarked that, "just when existential Marxism emerged, there was an abrupt shift in the French intellectual mood towards structuralism" (Poster, 1975, p. 306). This break occurred largely between 1965 and 1967, and one of its expressions was a structuralist Marxism initiated by Althusser. Poulantzas was an enthusiastic participant in this shift and was obviously influenced, if not fully converted, by the Althusserian school. Indeed, whilst his own existential-Marxist doctoral thesis was published in 1965, by 1967 he had completed the preparatory work for PPSC with its structuralist inspiration. But it was not just an epistemological break that Poulantzas underwent during this period. His main field of interest also shifted from the philosophy of law to the political sociology of the capitalist state. In studying the latter he also drew significantly on the work of Gramsci and other Italian Marxists.