Most love poems complain to the beloved. Wyatt's sonnet complains to a dream. The speaker addresses it like a servant who has failed in his duty: "Unstable dream, according to the place, / Be steadfast once, or else at least be true." The demand is quietly absurd, because instability is exactly what a dream is. But the speaker talks like a man bargaining with someone who has broken a promise, and the vocabulary of "true", "respect" and "case" gives his grief a faintly legal tone. He is pleading, and the poem's bitterness comes from knowing the plea is useless.
Judging by the poem, the dream has shown him the woman he longs for and let him embrace her ("My body in tempest her succour to embrace"), then snatched her away. He calls the loss "sudden" and the dream's kindness a "false feignèd grace". The two near-synonyms are piled together like a double accusation. His fear is that "tasted sweetness" will make the loss worse, and the poem confirms it. A glimpse of happiness hurts more than none.
The second quatrain is knotty, and readers disagree about exactly who does what. One image stands out, though: "this tossing mew". A mew was a cage for hawks, so I read it as the speaker's bed, a restless, confining place. "Tossing" suggests both sleeplessness and a ship in rough water, which prepares for "tempest" two lines later. Bed, cage and sea blur into one picture of a man trapped and thrown about.
At the sestet the poem splits the speaker into body and "sprite", or spirit. In the dream the body is "dead", and so "painless", while the spirit is "in delight". The line is a balanced antithesis, almost a tidy accounting of gains and losses. Then the question breaks the calm: why did the spirit not "keep it right", rather than "Returning, to leap into the fire?" I take this to mean waking, when the spirit returns to the body and to reality. The verb "leap" is the surprise. It makes the return sound voluntary, so the speaker blames his own spirit as well as the dream, as if he had thrown himself back into pain.
The last two lines turn this into a general rule: "Such mocks of dreams they turn to deadly pain." The grammar widens from one dream to dreams in general. "Deadly" also echoes "the body dead" from line nine. In the dream, being dead was painless. The truly deadly thing is waking up. The echo reverses the usual order of things, so that the dream-death is gentle and ordinary life is where the injury happens.
The form carries the same turn from hope to hurt. The rhyme scheme is abba abba cddc ee. The octave follows the Petrarchan pattern, and the poem then ends on a rhymed couplet in the English manner. The octave runs on only two rhyme sounds, "-ace" (place, grace, case, embrace) and "-ue/-ew" (true, rue, mew, renew). That repetition makes the opening feel like a mind circling the same few words and the same wound. The couplet then closes with a flat, almost proverbial verdict. The rhythm is basically iambic pentameter, but Wyatt squeezes "th'one, th'other" to fit the line, a small sign of how closely he is counting syllables. The opening phrase, with its heavy stresses on "Unstable dream", lands like a reproach.
The poem matters partly because of where it sits in the history of English verse. Wyatt is widely credited with bringing the sonnet into English, and here we can watch him working with an inherited form and bending it to his own purposes. It also matters because it is psychologically sharp. It takes a familiar experience, waking from a happy dream into disappointment, and makes it a small drama of blame, bargaining and self-reproach. Few poems about love give the speaker so unusual an opponent, or leave him so thoroughly outmatched.