The speaker begins with a blunt piece of advice: forget the future, which may never arrive, and distrust clever people who say otherwise. The only thing that can be counted on is the past, and the poem insists it belongs to you alone. It can't be denied or altered, and it is "burned onto your brain," a scar that stays.
Then the poem turns to a strange, quiet image. You are told to shake your past out onto a mat, like bedding or grain, and leave it in the summer sun. As it dries, it turns brittle, shrinks, twists and gathers dust. The figure watching, hunched on its haunches with head in hands, seems tired and resigned rather than angry. At nightfall, you gather up what remains: "the leftovers of your life."
The mood is sombre and still. There is no comfort offered, only a plain look at memory fading and curling away, yet still being all you have left.