The focus of the poem is the beauty of the eponymous, unnamed subject, whom the speaker frames in sublime terms. Using metaphor, Byron creates a portrait that is both rooted in the physical details of the subject and celestial and otherworldly in tone.

So powerful is the speaker’s encounter with the subject’s beauty that his description of her almost immediately vaults from the earth to the heavens. The first verb in the first line of the poem is “walks,” evoking a grounded image of the subject, but the speaker quickly introduces a simile to compare her to “the night / Of cloudless climes and starry skies.” This leaping transition is as imaginative as it is descriptive. While the metaphor allows the speaker to use the elements of the nocturnal scene to further render his portrait, it also conveys his own experience of confronting the sublime. That is, it dramatizes the ascendent emotions he feels as he experiences the beauty of the subject. Such is the speaker’s admiration that he compares the “gaudy” light of day unfavorably to the subject’s “tender light.” It is telling that the speaker uses metaphors drawn from nature, the classic locus of sublime inspiration, to express his praise of the subject.

Part of the speaker’s sublime reaction to the subject is his sense that he is beholding perfection. As he remarks in the second stanza, “One shade the more, one ray the less, / Had half impaired her nameless grace.” Developing the motif of darkness and light, the speaker claims that the subject represents an ideal state, a “nameless grace.” As in the first stanza, this claim of perfection is ambiguous, arguably revealing more about the speaker’s experience than about the actual subject herself. Given the speaker’s role as the mediator between the subject and the reader, the poem is chiefly a record of his experience of her beauty, underscoring the dictum that beauty is in the eye of the beholder.

In describing the subject of the poem, the speaker implicitly traces a line between her inward character and her outward appearance. This division reflects the concept of mind–body dualism, a longstanding and central facet of Western philosophy which holds that the mental and physical dimensions of reality are fundamentally distinct. Byron’s poem presents a vision of a woman in whom these categories ultimately blur together.

For the most part, the poem attends to the subject’s appearance or “aspect,” as the speaker says in the first stanza. Indeed, the first ten lines are entirely devoted to an approving description of her features. For example, the speaker praises the “nameless grace” that animates her “raven tress[es]” and casts a soft glow upon her face.

However, the poem introduces a dimension of interiority in the eleventh line, marking a transition from the body to the mind. Here, the subject’s face is described as the place “Where thoughts serenely sweet express / How pure, how dear their dwelling-place.” This description begins to establish a correspondence between the subject’s outward features and her inner thoughts. Just as the subject’s thoughts are “serenely sweet,” the physical locus of those thoughts, her face, is “pure” and “dear.”

This conflation between the physical and mental is taken further in the final stanza. The speaker offers more detailed descriptions of the subject’s face, noting the “smiles that win” and the “tints that glow” on her cheek and brow. These elements “tell of” the subject’s inner state. The “soft,” “calm,” and “eloquent” qualities of these facial features reflect the subject’s “goodness,” her peaceful mind, and her innocent heart. Indeed, this...