Few poems dismiss their subject as quickly as this one. The first two words, "Delusive Hope!", are already a verdict, and the rest of the sonnet carries out the sentence. The speaker orders Hope away, says goodbye to the landscape, and chooses a solitary retreat where she can "feed my soul, with luxury of woe." The central idea is a daring one: false comfort is worse than honest sorrow, and sorrow, once chosen, can feel like a kind of richness.
The first four lines are a trap of sorts. To show how fleeting Hope is, the speaker compares it to the last ray of sunlight, "more transient" than the light that "leads pale twilight to her dusky bed." Twilight becomes a tired woman being tucked in, and the day itself "sighs" as it leaves. The image is so lovely that it works against the speaker's argument. She calls Hope a deceiver in language as tender as anything Hope could offer. Even "Ling'ring" is a small irony, since the word describes the light, and it also suggests how reluctant the speaker is to let go.
The second quatrain turns from description to command: "Hence with thy visionary charms, away!" Hope is told not to scatter "the flow'rs of fancy" on her path and to take her "airy dreams" elsewhere. Where they belong, the poem says, is with sleepers on "peaceful pillows" and with "thoughtless brows" wearing a "garland gay." The key word is "thoughtless." Hope is for people who have not thought too hard, and the speaker's refusal implies that she has. Flowers and garlands are soft and decorative, and the poem sets them against much rougher things to come.
The form supports this change of mind. It is a Petrarchan sonnet, with an octave rhyming ABBAABBA and a sestet rhyming CDCDCD, in fairly regular iambic pentameter. The turn comes exactly where the form expects it, at line 9 with "Farewell." The sound shifts too. The octave's rhymes (ray, day, away, gay) are bright, open and almost cheerful, as if the music still belongs to Hope. The sestet's rhymes (farewell, dell, dwell, and flow, forego, woe) are lower and longer. The long "o" sounds in the last three lines drag out like a sigh, and "woe" gets the final word.
The goodbyes in the sestet are the most interesting part. The speaker bids farewell to "low vallies," "dizzy cliffs," "small vagrant rills," a "dark bosom'd labyrinth" and a "thorny dell." Read in order, the places grow darker and more enclosed, moving from open heights and flowing streams to a maze and a thicket. The rills "murmur," almost as if complaining, and the labyrinth is "bosom'd," held in a close, shadowed embrace. These are also places where the speaker might expect to wander, so the farewell has an odd double effect. She gives up the landscape in order to "hide" in a place of inward thought. The thorns also answer the earlier flowers. Hope offered blossoms, and the speaker walks off toward the brambles.
The ending depends on a paradox. "The task be mine all pleasures to forego" makes grief sound like a duty, something to be done with discipline. Then "luxury of woe" turns it into an indulgence. The oxymoron is the heart of the poem, and it admits that the speaker does not really abandon pleasure. She swaps one for another. Meditation, personified as something that "loves to dwell" in hidden places, is a better companion than Hope, because it makes no promises it cannot keep.
What makes the sonnet worth reading is this tension between what the speaker says and how she says it. She rejects charm with charm, renounces beauty in beautiful lines, and calls her sorrow a feast. Whether she is fully sincere is left open, and the poem is more interesting for that. The fourteen lines also show how well the sonnet suits an argument with oneself, with a crisp turn at the ninth line and a last line that sounds like both a surrender and a choice.