The speaker lights a cigarette after seven years of quitting, and the poem follows that first smoke as it happens. At first there is almost tender delight: the cigarette is a "little smoky thumb," and the speaker's head feels light, like a flower that has just been pollinated. The body, it turns out, hasn't forgotten anything. Even though every cell has been replaced since quitting, the fingers still know how to handle matches, paper and ashtray.
Then the mood shifts. The speaker wonders what other "secret flaws" the "new/old body" might have inherited, and watches the cigarette burn down with "growing detachment." That cooler, watchful tone suggests some doubt or regret about giving in. The ending looks back to the speaker's very first cigarette, in Japan, 21 years earlier, when they didn't know what to do next. The poem circles from clumsy beginner to practiced habit, leaving a mix of pleasure, unease and nostalgia.