In his 1957 Mythologies, Roland Barthes proposes a second‐order semiological system, in which a familiar sign is repurposed to become a new signifier and in the process mythologises the previous sign system. This article adapts this principle to musical topics in twentieth‐century music, using the case study of the eighteenth‐century topical universe as it appears in Sergey Prokofiev's two String Quartets.I approach this from two directions, exploring in turn the mechanics of internal relationships and wider historical‐political implications. First, drawing upon William Caplin's concept of formal functions and their various possible associations with topics (Caplin 2005), I propose that topics with formal associations can express formal functions without the requirement for clarity in the primary parameters of harmony, tonality, grouping and cadence. Accordingly, they signify on a second‐order plane. The recurring Mannheim rocket in the first movement of Prokofiev's String Quartet No. 1 (1931) provides a case study. Second, I demonstrate the parallels between a second‐order system and key tenets of socialist realism. Concepts such as dostupnost′ (making the work understandable to everyone) and opora na klassiku (based on past Classical models) echo Barthes's model, as meaning is drawn from reference to Enlightenment‐associated art as a whole, rather than the individual topics. I demonstrate these principles in practice with reference to Prokofiev's Quartet No. 2 (1941). Together, these second‐order perspectives show the deeply rooted reliance on eighteenth‐century semantics in Prokofiev's music and their wider aesthetic implications.