Joseph Severn’s sketch of the dying Keats, frontispiece of Letters of John Keats to Fanny Brawne (1878), public domain Last week, New York District Attorney Alvin Bragg, best known for prosecuting Donald Trump on the charge of falsifying business records to cover up payments of hush money to Stormy Daniels, had an easier task: handing back 17 stolen books to the Whitney family. Among them was a beautifully bound collection of eight manuscript letters. Pasted as frontispiece was a silhouette of a slender woman holding a fan. As the New York Times was the first to report , it was recovered last year by a sharp-eyed bibliophile, Joshua Mann, co-owner of B & B Rare Books on Madison Avenue. A young man had come in, attempting to sell the volume. Immediately suspicious, Mann persuaded the customer to let him retain it so that he could establish its authenticity and set a price.…