The poem treats a stone as something that refuses to be solemn. The opening lines push back on the old habit of seeing stones as monuments or graves, heavy with seriousness. Instead, the speaker says a stone must be open to "time and ruin," meaning it has to accept weathering, cracking, and slow decay rather than standing for permanence.
The third stanza is odd and interesting. The stone approaches the ground "with no earhole," which suggests it can't listen or respond. It simply settles down, deaf and passive, into the earth. Then comes a surprising image: something "green and slow / like a ship of fools." Moss or lichen seems a likely picture, creeping over the surface, though the poem never says so outright.
The mood is calm, dry, and a little playful. The speaker seems to accept decay without sorrow, even with some humor. The title hints that the stone is almost a mind, a landscape of thought, drifting quietly toward ruin.