Swinburne's sonnet stages a small drama in fourteen lines: a bright, confident figure is shown at sunrise, warned about what the afternoon may bring, and finally handed a piece of advice that cancels her out. Hope appears as a personified young woman ("her wide wings") with "eyes enkindled as the sun's own sphere." She looks "Godward," past the "blind men" who "grope / Round the dark door that prayers nor dreams can ope." The poem suggests this door is the unanswerable mystery that no prayer or fantasy can force open. Hope doesn't bother with it. She simply flies, and even enjoys the darkness, because it "gives her wide wings play." Her joy needs something to soar against, and the poem quietly implies that she depends on the very uncertainty she ignores.
The octave closes with a warning: "fear / At noon may rise and pierce the heart of hope." The time words matter. The poem begins at dawn, and noon is when the sun is highest and shadows are shortest, so Hope is least protected just when she looks strongest. Fear is not an outside enemy but something that grows out of hope itself. To hope for something is to be able to lose it.
The sonnet's construction makes this point audibly. Its octave uses only two rhyme sounds, in the pattern abba abba. The "-ope" rhymes (cope, grope, ope, hope) and the "-ear" rhymes (sphere, cheer, dear, fear) are the title's two words echoing through the lines. They also interlock, with the "fear" rhymes enclosed by the "hope" rhymes, as though one emotion were wrapped around the other. The line "pierce the heart of hope" is the last rhyme of the octave, so hope is literally the final word before the poem turns.
The turn arrives at line nine, where "Then, when the soul leaves off to dream and yearn" shifts from youthful brightness to something sober. Eyesight is a recurring thread: Hope's blazing eyes, the "blind men," and now truth, which may "purge her eyesight." That verb is medical and severe, suggesting that clear vision is a cure rather than a gift. The pronoun is slightly ambiguous, and "her" could refer to the soul or to Hope herself, but either way, seeing clearly is painful and necessary. What the cleansed eye discerns is something that, "once being known, leaves time no power to appall." Swinburne never says what this knowledge is. The poem hints at it through the dark door and the passage of time, which suggests an acceptance of mortality and uncertainty.
The final line is the poem's plainest. After the elaborate vocabulary of "aërial cope" and "enkindled," it is almost entirely monosyllabic: "Hope thou not much, and fear thou not at all." It comes in quotation marks, as "the kind wise word that falls from years that fall." The echo of "falls" and "fall" lets the voice of age drift down like autumn leaves, and it quietly counters the rising, winged image of Hope earlier. Even the old-fashioned "thou" feels like a elder's voice speaking directly.
The advice is not symmetrical, and that is the most interesting detail. Youth is told to hope "not much," which allows a little hope, but to fear "not at all." The reasoning seems to follow from the sestet: if real knowledge leaves time no power to appall, nothing remains to be afraid of, while a small hope may still be harmless. This is not cheerful optimism or gloomy pessimism but a kind of stoic calm, a balance that survives both the sunrise and the noon.
The poem is also a fine example of what the sonnet form can do. A Petrarchan-style octave and a turning sestet fit an argument that moves from youth to age, and the sestet's rhymes (yearn, discern, learn; appall, fall, all) land on that final, deflating "all." It is a tightly controlled poem about letting go of control, and its refusal to promise either happiness or despair is what keeps it memorable.