Like her older brother, Benjamin, Jane Franklin was a passionate reader, a gifted writer, and a shrewd political observer. While he was rich and famous, she was poor and obscure. Yet Jane was a constant presence and influence in her brother’s life—in fact, Benjamin Franklin wrote more letters to her than to any other individual.

Historian Jill Lepore explores this extraordinary, overlooked life in a discussion of her new book Book of Ages: The Life and Opinions of Jane Franklin.

Lepore is the David Woods Kemper ’41 Professor of American History at Harvard University and a staff writer at The New Yorker.