On December 28, 1817, the painter Benjamin Robert Haydon hosted what he referred to in his diaries and autobiography as the "immortal dinner." He wanted to introduce his young friend John Keats to the great William Wordsworth and to celebrate with his friends his most important historical painting thus far, "Christ's Entry into Jerusalem," in which Keats, Wordsworth, and Charles Lamb (also a guest at the party) appeared. After thoughtful and entertaining...