When John Keats and Benjamin Robert Haydon were introduced in late 1816, the two men could hardly have been more different. Keats was a virtually unknown young apothecary who had a passion for poetry and a growing belief in his own abilities. Haydon was several years older and one of the most famous painters in London, a man who was certain that he was destined to create a new Renaissance in English art. Today, Haydon is almost forgotten but Keats...