What is the importance of the title in the novel, Tender Is the Night?

The title comes from a line in John Keats's "Ode to a Nightingale": The poem, with its forlorn images of drinking, fits the character and tone of the book. As a young writer Fitzgerald was profoundly influenced by Keats. While in Italy, in chapter XXII of Book Two, on his way back to his hotel where a note from Rosemary is awaiting him, Dick feels his "spirits soared before the flower stalls and the house where Keats had died."