Keats's song, In drear nighted December（written in December 1817）, has a strong connection with Isabella, which Keats starts to compose in February or March 1818. The statement if the song, “The feen of not to feel it... Was never said in rhyme”, may rightly be regarded as the poet's manifesto that he is to write, having finished his Endymion, a new poem whose theme ought to be “The feel of not to feel [passed joy]” ; Isabella is not anything other than this new poem, one aim of which is to outdo Leigh Hunt's The Story of Rimini. The connection between the song and Isabella seems to have taken place through Keat's reading of the story of Paulo and Francesca in Cary's Dante, a part of which-- . “Hell”, IV , 126 --Keats quotes in his review of Edmund Kean published in the Champion, 21 December 1817. In Cary's translation Francesca in Cary's laments her fate in Hell thus : “ No greater grief than to remember days / Of joy , when misery is at hand” (“Hell” , V , 118-19) . These lines deal with the same motif not only as Keats's song but also as Isabella.“The feel of not to feel [passed joy]” is , on the one hand , the kind of 'feel' hat such 'spirits' as Francesca , Paulo, or Lorenzo must go thought in Hell. Keat's attempt in Isabella is to fully dramatize the hellish pain of memory which Isabella is to some extent , and Lorenzo's ghost to a greater extent, forced to feel both in and beyond this world. “The feel of not to feel it ”is, on the other hand, the aching 'feel'--the cause of Keats's melancholy--from which the poet cannot relieve himself for long in real life ; hence come almost all Keats's major poems where the poet focuses on the theme of 'nelancholy' in one way or another , groping for a way out of his own distress. The subject of 'melancholy' also unites Keats's song with the “Cave of Quietude” lines (Endymion, IV , 512-48), in which is suvtly suggested that “The feel of not to feel it” can lead to saving a depressed soul like Endymion's or Keats's in a mysterious way. However, because of the temporariness and uncertainty intrinsic in its nature, this sort of “sorrow's mysteries”(Ode on Melancholy, 1. 8) is very likely to end up with another, often severer , round of melancholy. For Keats “The feel of not to feel [passed joy]”is double－edged. Without this 'feel' which works in collaboration with the poet's “Negative capability”, most of Keat's best poemes would not have been produced ; yet it is the same 'feel'　that causes “the destruction of [his] health” as Keats confides to his sister, Fanny, just half a year before his death.