Taking a series of period courses arranged in chronological order seems the natural and obvious way for students to learn history. But an odd thing happens when these courses are not connected to one another, as they rarely are in the college curriculum. Since students experience each course as a self-contained unit, they have no incentive to remember one period once they move on to the next. Describing a course he taught in a required literary history sequence, the author is struck not only by his students’ inability to make connections with the previous course in the sequence but also by their evident surprise at being asked to recall what they had studied in any previous course. This essay—a guest column in Common Knowledge—goes on to generalize the implications of the incident, arguing that, paradoxically, the effect of period courses is to erase the sense of historical sequence, continuity, and contrast from students’ minds and thereby to erase history itself. The point is not that there is something wrong with dividing history into period courses—some such division is unavoidable and necessary—but that unless period courses are connected, students will come away with an ahistorical view of history.