Please comment upon these lines from "Ode to a Nightingale" by Keats.
Forlorn! the very word is like a bell
To toll me back from thee to my sole self!
Adieu! the fancy cannot cheat so well
As she is famed to do, deceiving elf.
Adieu! adieu! thy plaintive anthem fades
The lines you have quoted come from the first half of the last stanza of this famous Romantic poem, in which the speaker has a kind of out-of-body experience and reflects and meditates upon the human condition thanks to the song of the nightingale that he listens to. As the song of the nightingale ends, so the poet is brought back to earth, and this is what occurs at the beginning of this quote.
Note the use of the word "Forlorn." This is of course a word that is used in the previous line of hte poem, and the repetition underlines the speaker's mood and echoes the sound of the tolling bells that he compares it to, which calls the speaker back from his reverie to harsh reality. Although, in the middle of the poem, the "fancy" or imagination that is spoken of here is shown to operate in full power, transporting the speaker away from the trials and tribulations of life on earth, at the same time, the power of fancy and its limitations are indicated here, as the speaker refers to her as a "deceiving elf." The tone is one of reflective resignation as the speaker bids farewell to the "plaintive anthem" of the nightingale and is forced to rejoin reality.