Lines 4–8 are unclear, for it is not certain if “the hand . . . and the heart” belong to the sculptor, in which case the idea is that the sculptor “mocked” (“mimicked,” “imitated in stone”) the passions and “fed” them by creating them in stone, or if the hand and the heart belong to Ozymandias, whose hand mocked the passions of his foes and whose
heart fed his own passions.
“Ozymandias,” although one of the monuments of English poetry, has a few cracks in it. Many people find line 8 incomplete in sense: the heart that fed what, or fed on what? From its rime scheme, we might think the poem a would-be Italian sonnet that refused to work out.
The structure of the poem helps establish remoteness: Ozymandias’s words were dictated to the sculptor, then carved in stone, then read by a traveler, then told to the first-person speaker, then relayed to us. Ironies abound, more subtle than Guiterman’s. A single work of art has outlasted Ozymandias’s whole empire. Does that mean that works of art endure (as in “Not marble nor the gilded monuments”)? No, this work of art itself has seen better days, and soon (we infer) the sands will finish covering it. Obviously, the king’s proud boast has been deflated, and yet, in another sense, Ozymandias is right. The Mighty (or any traveler) may well
despair for themselves and their own works, as they gaze on the wreckage of his one surviving project and realize that, cruel as Ozymandias may have been, time is even more remorseless.
According to the Greek historian Diodorus Siculus, Ozymandias was apparently a grand, poeticized name claimed for himself by the Egyptian pharaoh Rameses II. Diodorus Siculus saw the king’s ninety-foot-tall statue of himself, carved by the sculptor Memnon, in the first century B.C. when it was still standing at the Ramesseum in Thebes, a mortuary temple.
The line "look on my works ye mighty and despair!" implies a certain contemptuousness for anyone who does not have power, command, or influence in which a statue can be built fore them.
For anyone else coming to this page, boulderbill's interpretation can't be called wrong, but he's wrong to say that the passions were "clearly the king's". I invite anyone to visit Poemshape and join the discussion on Ozymandias (if you want to see some of the ways this line can be interpreted). Utlimately, you will have to interpret the lines for yourself. Don't let anyone tell you they know the one right way - especially teachers and professors. There's no reason you can't be as informed as any of them.
While epollock has some interesting things to say, I respectfully disagree with his answer to your question as the meaning is apparently clear...
The hand that mocked (recreated) those passions (in the visage) was that of the sculptor.
The heart that fed those (original) passions was clearly the king's.