The speaker imagines a "we" that is slowly disappearing, becoming ghosts of what it once was. The central image is smoke lingering over a pyre after the fire has died: something left behind once the real energy is gone. The group haunts "lifeless empty spaces," suggesting a presence that no longer has any force or purpose.
The tone is resigned rather than angry. The "destructive passions" are dwindling, but that doesn't feel like peace. Instead, the speakers give in to a "predestined recession," as if fading were always going to happen. Words like "quieted endlessly" and "woeful depths" make this surrender feel heavy and sad. By the end, the speakers are so faint that nobody believes in them, and they survive only in "bygone memories."
The mood is quiet, mournful and hollow. The short, trailing lines, especially the lone "And linger," mimic the way something thins out and slips away.