To tell the history of India through 50 personalities, first a radio project for the BBC and now a handsomely produced book, Incarnations, has perhaps been one of Sunil Khilnani’s more ambitious and demanding projects, not least because of its non-academic format. The author—historian and director of the India Institute at London’s King’s College—travelled thousands of miles through the country to research for it and the outcome is a living, throbbing, riveting glimpse into these great minds who shaped India. “It is not up to the state to define nationalism on everyone’s behalf,” Khilnani tells Satish Padmanabhan in an interview. Excerpts: