HAMLET                     What is he whose grief

Bears such an emphasis, whose phrase of sorrow

Conjures the wandering stars and makes them stand

Like wonder-wounded hearers? This is I,

Hamlet the Dane.

LAERTES                    The devil take thy soul!         (5.1.243-247)

Hamlet knows it’s Laertes—this is not a request for information—it’s more a way of Hamlet saying, I’M BAAAAACK! (He doesn’t come out of this encounter well, it’s astonishingly self-centred, self-aggrandizing.) He recognises Laertes’s grief, he can speak very readily in the same idiom: what is he whose grief bears such an emphasis, is so extreme, so heartfelt, whose phrase of sorrow conjures the wandering stars and makes then stand like wonder-wounded hearers?Hamlet’s back indeed, and he’s still got it, pounding out the verse even as he describes someone else doing likewise: Laertes’s articulation of his sorrow makes the stars not simply stand still, but to wonder, struck dumb? Hamlet recognises this as a cosmos-shaking grief—and he knows what that feels like—but this is just prelude to his own announcement, arrogant and absolute. Who are you? Well, I know who you are, and I can appreciate that you’re upset, but this is I, Hamlet the Dane. I’m back, and I’m here to claim my birthright (if, as is often suggested, the Dane means the rightful Danish king). If Laertes thought he was having a terrible day already, it just got unbelievably worse, he’s not ready for this, this wasn’t in the plan: the devil take thy soul! you bastard! how dare you come here like this?

Editors supply various stage directions: does Hamlet leap into the grave at this point? (Theatrically tricky, although there’s some early evidence that he did.) Does Laertes jump out and attack him? Easier, but still needs care (and agility, and excellent quads).