Many aspects of behavior are guided by dispositions that are relatively durable once formed. Political opinions and phonology, for instance, change largely through cohort succession. But evidence for cohort effects has been scarce in artistic and intellectual history; researchers in those fields more commonly explain change as an immediate response to recent innovations and events. We test these conflicting theories of change in a corpus of 10,830 works of fiction from 1880 to 1999 and find that slightly more than half (54.7 percent) of the variance explained by time is explained better by an author’s year of birth than by a book’s year of publication. Writing practices do change across an author’s career. But the pace of change declines steeply with age. This finding suggests that existing histories of literary culture have a large blind spot: the early experiences that form cohorts are pivotal but leave few traces in the historical record.