In Sylvia Plath’s “Mirror,” the mirror serves as the speaker who describes the different things it sees.
The theme of feminism comes into play in the second stanza, which focuses on the unnamed woman who gazes at herself in the mirror daily. In exchange for reflecting her “faithfully,” the woman “rewards [the mirror] with tears and an agitation of hands.” This shows that the woman is unhappy with what she sees reflected in the mirror, her appearance as it truly is. The fact that the woman looks in the mirror at the beginning of each day implies that she is somewhat obsessed with her appearance. Specifically, the woman despised the “old woman” she is becoming “like a horrible fish.”
This relates to feminism because of women’s often fraught relationship with beauty and aging. Society’s ideal woman is both beautiful and young, so women tend to become more self-conscious as they age. The mirror symbolizes society’s obsession with beauty, which unduly impacts women more so than men. Plath is voicing some of the anxieties women experience about their changing bodies and faces, which can sometimes consume a woman’s thoughts and even daily routines.
The emphasis on beauty for women is a feminist issue because we tend to view older men as handsome/wise while degrading older women as hags.