Themes are the fundamental and often universal ideas explored in a literary work.

The Dubious Nature of Objectivity

A central theme in “Mirror” relates to the dubious nature of claims to objectivity. Both versions of the poem’s speaker—first the mirror, then the lake—make claims about their capacity to reflect whatever is in front of them in an objective way. The mirror makes a particularly strong claim for their objective point of view in lines 1–4:

     I am silver and exact. I have no preconceptions.
     Whatever I see I swallow immediately
     Just as it is, unmisted by love or dislike.
     I am not cruel, only truthful.

Yet for all that the mirror claims to reflect what they see without distortion, it soon becomes clear that the mirror may be more biased than they’d like to admit. Specifically, they note that they have stared at the opposite wall “so long / I think it is part of my heart” (lines 7–8). Far from being a distanced and objective observer, the mirror has grown attached to the world it sees. Much like the mirror, the lake grows attached to the aging woman who comes for a daily swim. Though they claim to reflect the image of this woman “faithfully” (line 13), they close the poem with a startling—and likely unfaithful—description of the woman that likens her face to that of “a terrible fish” (line 18).

Time’s Relativity

Compared to humans, inanimate beings experience time on a much vaster scale. The metal and glass that make up the mirror take much longer to deteriorate than the human body does. Likewise, the lake is a geological feature that came into existence over millions of years and may exist for millions more. Relative to such vast time scales, an individual human life seems to pass at a rapid rate. For their part, the mirror reveals how differently they perceive time in lines 7–9:

                   I have looked at it so long
     I think it is part of my heart. But it flickers.
     Faces and darkness separate us over and over.

Here, the mirror describes how the wall across from them passes in and out of view, interrupted by people’s faces and by the recurring “darkness” of night. From the mirror’s perspective, both faces and darkness pass by so quickly that they create a rapid flickering effect, not unlike a sped-up film. In a similar way, the lake experiences the woman’s life as passing in a flash. They imply as much in the poem’s closing lines, where they emphasize the suddenness of the transition from girl to old woman: “In me she has drowned a young girl, and in me an old woman / Rises toward her day after day” (lines 17–18).

Life’s Brevity

The relativity of time points to another important theme related to life’s brevity. The opening stanza gestures to this theme in a glancing way, through its representation of the mirror’s perception of time. To the mirror, days pass by so fast that the alternation between day and night creates a rapid flickering effect. Seen from this perspective, human life unfolds at high speed. Much like a time-lapse video of a flower blooming and wilting showcases the fleeting nature of botanical life, the mirror’s high-speed vision draws attention to the brevity of human life. The poem’s second stanza, narrated by the lake, develops this theme further. The lake speaks of a woman who makes daily pilgrimages to the water. The lake registers that they’ve become “important to [the woman]” (line 15). Though they don’t say so explicitly, it’s also evident that the woman has become important to the lake. The lake’s attachment to the woman comes across in the poem’s final lines (16–18):

     Each morning it is her face that replaces the darkness.
     In me she has drowned a young girl, and in me an old woman
     Rises toward her day after day, like a terrible fish.

The lake has gotten used to seeing the woman’s face every day, but the way she’s aged from a girl to an old woman causes the lake anxiety and forces them to reckon with just how brief a human life really is.