“Forgetfulness” examines the effect of aging upon the “you” figure and, by extension, the reader. Collins plays off of the forgetfulness that accompanies aging; the “you” figure’s memories have “retire[d] to the southern hemisphere of the brain / to a little fishing village where there are no phones” (Lines 6-7). The poem approaches aging with a playful tone, suggesting a certain degree of humor in this loss. The speaker treats aging as inevitable, noting that even as the “you” tries to cling to memories and knowledge, life moves on, the body ages, and “Whatever it is you are struggling to remember […] has floated away down a dark mythological river” (Lines 13, 16). The allusion to the Lethe and the underworld re-emphasizes the idea of oblivion (one translation of the Greek lethe) and introduces an element of uneasiness and fear of the unknown.

The speaker is sympathetic to the “you” figure’s attempt to avoid aging, as the “you” attempts to once again memorize the order of the planets (Line 10) and gets up in the middle of the night to look up the date of a famous battle (Lines 20-21). Although aging is inescapable, the speaker acknowledges the inherent loss and the ways in which it can unmoor a person.