"Life cycle" follows a fire through stages, and it's easy to read that fire as a life, or maybe as a spirit, an energy, or an idea. It begins big and loud: "blown up into uncommon fame." Then it shrinks and goes inward. It lives "in the people," but "something nobody knows," as if it has become a hidden force no one can name. Next it sits "under our own seats / pretending to sleep," which feels both close and a little threatening, like something waiting to wake. The last image is the smallest: a fire "gone out on foot / naked and thin," stripped of everything and walking away.
The speaker doesn't say how they feel outright. The tone is quiet and observant, with a hint of sadness at fame fading into bareness. Still, the fire never fully dies. It just changes form, and that leaves the mood somewhere between loss and a stubborn, lingering warmth.