In this poem, a mirror describes its existence and its owner, who grows older as the mirror watches.
The mirror first describes itself as “silver and exact.” It forms no judgments, instead merely swallowing what it sees and reflecting that image back without any alteration. The mirror is not cruel, “only truthful.” It considers itself a four-cornered eye of a god, which sees everything for what it is.
Most of the time, the mirror looks across the empty room and meditates on the pink speckled wall across from it. It has looked at that wall for so long that it describes the wall as “part of my heart.” The image of the wall is interrupted only by people who enter to look at themselves and the darkness that comes with night.
The mirror imagines itself as a lake. A woman looks into it, trying to discern who she really is by gazing at her reflection. Sometimes, the woman prefers to look at herself in candlelight or moonlight, but these are “liars” because they mask her true appearance. Only the mirror (existing here as lake) gives her a faithful representation of herself.
Because of this honesty, the woman cries and wrings her hands. Nevertheless, she cannot refrain from visiting the mirror over and over again, every morning. Over the years, the woman has “drowned a young girl” in the mirror, and now sees in her reflection an old woman growing older by the day. This old woman rises toward her out of the mirror like “a terrible fish.”
In this short but beloved poem, the narrator is a wall mirror in what is likely a woman's bedroom. The mirror is personified - that is, it is endowed with human traits. It is able to recognize monotony, commenting on the regularity of the wall that it reflects most of the time. Further, while it does not offer moral judgment, it is able to observe and understand its owner (the woman) as she grapples with the reality of aging.
Compared to most of the others in Plath's oeuvre, this poem is not particularly difficult to analyze. Though the speaker is a mirror, the subjects are time and appearance. The woman struggles with the loss of her beauty, admitting each day that she is growing older. Though the woman occasionally deludes herself with the flattering "liars" candlelight and moonlight, she continually returns to the mirror for the truth. The woman needs the mirror to provide her with an objective, unadulterated reflection of self, even though it is often discomfiting, causing her "tears and an agitation of hands." The mirror is well aware of how important it is to the woman, which evokes the Greek myth of Narcissus, in which a young man grows so transfixed with his own reflection that he dies.
Some critics have speculated that the woman is vexed by more than her changing physical appearance. They posit that the woman is observing her mind, her soul, and her psyche, stripped of any guile or obfuscation. By seeing her true self, she becomes aware of the distinction between her exterior and interior lives. In other words, she might be meditating on the distinction between a "false" outer self of appearance, and a "true" inner self. After Plath's 1963 suicide, many critics examined the writer's different facets, contrasting her put-together, polite, and decorous outer self with her raging, explosively-creative inner self. Perhaps Plath is exploring this dichotomy in "Mirror." The slippery and unnerving "fish" in the poem may represent that unavoidable, darker self that cannot help but challenge the socially acceptable self.
The critic Jo Gill writes of "Mirror" that even as the mirror straightforwardly describes itself as "silver and exact," it feels compelled to immediately qualify itself. Gill writes, "as the poem unfolds we see that this hermetic antonym may be a deceptive facade masking the need for communion and dialogue." The mirror actually dominates and interprets its world, and thus has a lot more power than it seems to suggest. It does not merely reflect what it sees, but also shapes those images for our understanding. Gill notes that the poem is catoptric, meaning that it describes while it represents its own structure; this is down through the use of two nine-line stanzas which are both symmetrical, and indicative of opposition.
The second stanza is significant because it, as Gill explains, "exposes...the woman's need of the mirror [and] the mirror's need of the woman." When the mirror has nothing but the wall to stare at, the world is truthful, objective, factual, and "exact," but when the woman comes into view, the world becomes messy, unsettling, complicated, emotional, and vivid. Thus, the mirror is "no longer a boundary but a limninal and penetrable space." It reflects more than an image - it reflects its own desires and understanding about the world.
Overall, "Mirror" is a melancholy and even bitter poem that exemplifies the tensions between inner and outer selves, as well as indicates the preternaturally feminine "problem" of aging and losing one's beauty.