Book excerpt: On Diary is the second collection in English of the groundbreaking and profoundly influential work of one of the best-known and provocative theorists of autobiography and diary. Ranging from the diary’s historical origins to its pervasive presence on the Internet, from the spiritual journey of the sixteenth century to the diary of Anne Frank, and from the materials and methods of diary writing to the question of how diaries end, these essays display Philippe Lejeune’s expertise, eloquence, passion, and humor as a commentator on the functions, practices, and significance of keeping or reading a diary. Lejeune is a leading European critic and theorist of diary and autobiography. His landmark essay, "The Autobiographical Pact," has shaped life writing studies for more than thirty years, and his many books and essays have repeatedly opened up new vistas for scholarship. As Michael Riffaterre notes, "Lejeune’s work on autobiography is the most original, powerful, effective approach to a difficult subject. . . . His style is very personal, lively. It grabs the reader as scholarship rarely does. Lejeune’s erudition and methodology are impeccable." Two substantial introductory essays by Jeremy Popkin and Julie Rak place Lejeune’s work within its critical and theoretical traditions and comment on his central importance within the fields of life writing, literary genetic studies, and cultural studies.