A once-stolen collection of letters written by the Romantic poet John Keats to his fiancée Fanny Brawne will be sold at Sotheby’s New York this June with an estimate of $1.5 million to $2.5 million. The group of eight letters, tastefully bound in a leather volume, date from 1819 to 1820, a period when Keats was suffering from tuberculosis and often conducting the courtship through the written word. The two had met as neighbors in Hampstead, then a leafy village overlooking London, with Keats telling his brother that he found her “beautiful and elegant, graceful, silly, fashionable. and strange.” They became secretly engaged in late 1819. Part of a broader corpus of nearly 40 letters, the missives reveal the ardor of young love, as well as Keats’s reflections on beauty, fame, and his own mortality—he would die in Rome in 1821 at the age of 23. One of eight autograph letters signed by John Keats. Photo courtesy Sotheby’s.…