The poem opens with the image of an older person, often perceived as a woman, “nodding by the fire” (Line 2). The person is described as “old and grey and full of sleep” (Line 1). “Fire” in this context represents the woman’s former life, which she knows has passed and is soon burning out. Later in the poem, the woman bends “down beside the glowing bars” (Line 10) to stoke this fire with the memory of her lover. The “glowing bars” represent the woman’s former life and her youthfulness, which passed quickly. The poem concludes with Love hiding “his face amid a crowd of stars” (Line 12). Stars are a fixed point of light. “Stars” (Line 12) is the poem’s final word, with its placement representing the plane beyond life that awaits the woman after her life ends.

Aging and life’s brevity are the primary motifs in not only “When You Are Old,” but also many of Yeats’s other poems. The poem establishes the motif of aging from its beginning, opening with the image of a person who is “old and grey and full of sleep” (Line 1). Words and phrases like “dream” (Line 3), “shadows” (Line 4), and “changing face” (Line 8) facilitate this motif.