The poem is only a few lines long, but it packs in a surprisingly full picture of aging. A man, it says, "grows into his own rant," as if bitterness and complaint were something he slowly becomes, the way a person grows into a coat. Alongside that come "rot and tears," which suggest the body decaying and the grief that goes with it.
Then the poem shifts to a comparison: he is like a monk in a habit, heading off "to play with his bells." The image is odd and a little tender. Bells might mean a monastery's calling bells, but they also sound childlike, almost like toys, so the man seems both solemn and silly.
The speaker doesn't seem to scorn him. The tone is wry, affectionate, and a bit sad. Ranting and decay look unavoidable, yet the poem finds something gentle in them, a kind of ritual or play that carries him through.