In just three lines, this poem sets a quiet morning scene and then lets it shrink down to almost nothing. It begins with rain, a soft, ordinary sound, and then narrows to a single dish of marrow bones. The last line makes a startling claim: that this dish is all that is "left in the world."
Of course, the world hasn't literally vanished. The line reads more like a feeling, the way a gray, rainy morning can seem to wipe out everything beyond the window. The speaker seems alone, perhaps a little hollowed out, and the bones sit there as what remains after a meal has been eaten.
Marrow is the inner part of a bone, so the title points toward something essential and stripped down. The mood is hushed, bare, and a bit melancholy, though not despairing. There is also a strange comfort in the image: even when everything seems gone, something nourishing is still on the table.