Novelistic sentences dramatically simplified in structure and contracted in length throughout the 1800s and early 1900s. This article places these changes within the longer process of grammatical “weakening” (the loss of inflection for regular order). Building on the linguist Otto Jespersen's theorization of the relationship between grammar and social change, the article argues that the grammar of modern novels, irrespective of their representational content or individuating style, has a proleptic relation to the rise of mass society. The problems that Georg Lukács and Theodor Adorno would articulate in terms of reification and alienation are already enacted grammatically as words break down into their linguistic properties and increasingly derive their meaning through placement. The article focuses on three pivotal moments of this development: the “prosification,” or the virtual conflation of poetic and prosaic syntax, in the Romantic era; the conspicuous intensification of uninflected prose that is generally taken to be the stylistic innovation of the modernist era exemplified by Virginia Woolf; and the sedimentation of syntax into generic idioms in subsequent decades in such writers as Doris Lessing and Samuel Beckett. Novelistic grammar, precisely by prefiguring the social changes to come, models a rationality that constrains the possibilities of moving past those changes. By analyzing the contradictions constitutive of novelistic grammar, this article questions what is reinforced or foreclosed in the endless generativity of grammar.