The poem starts with a blunt claim: a man's head is not the same shape as the world. His mind, in other words, doesn't match reality, but it is content with itself anyway. It "satisfies itself / there," as if he has settled comfortably inside his own thoughts.
Then the poem lurches into fragments: an offer of grapes, two breasts, someone breathing behind them, ships that have just gone back out. These images feel like things passing through his mind, or pieces of the world he can only glimpse and half-grasp. They are sensual, even tempting, but they arrive without explanation or connection. The last line, "He makes the round in his head," suggests he keeps circling the same ground, going over these scraps in a closed loop.
The speaker seems detached, watching rather than judging. The mood is quiet, dreamy, and slightly ironic: a mind turning inward, pleased with its own small circuit while the larger world stays just out of reach.