BARNARDO: It would be spoke to.
MARCELLUS: Speak to it, Horatio.
HORATIO: What art thou that usurp’st this time of night,
Together with that fair and warlike form
In which the majesty of buried Denmark
Did sometimes march? By heaven, I charge thee speak.
When last we left our supporting cast — Barnardo the Paranoid, Marcellus the Chatty, and Horatio the (former) Skeptic, they were in the process of having their souls demolished by the appearance of the Ghost. Marcellus, having seen the spectre twice before, is able to muster up enough courage to speak, but not to the Ghost itself. Instead, he tells Horatio to speak to it, since he is a scholar and by extension, presumably, a ghostbuster.
Now, three lines later, Barnardo and Marcellus both repeat the injunction. Horatio isn’t just along for a free tour of the battlements at night; he has a job to do. So he puts on his best authoritative tone, which must be difficult considering the Ghost is (a) a supernatural entity, and (b) a king. Note that, unless the audience is wearing universal translators, he does not speak Latin to it. Maybe that’s why he doesn’t get a reply.
Or maybe Horatio is simply being rude. “Usurp” is an odd choice of metaphor with which to open. It implies that the Ghost has unlawfully intruded upon “this time of night” (even though it will come to be established that midnight is the perfect time for ghosts to walk the earth). The next line, starting with “together,” adds a second charge of usurpation: not only has the Ghost stolen the time, he has also stolen the dead King’s appearance. Though he is terrified, Horatio has the guts to accuse the Ghost of being an imposter — the implications of which will be explained in Act 1, Scene 4.
“The majesty of buried Denmark” is an interesting phrase. It uses a synecdoche to associate “Denmark” the country with its head of state, something that Shakespeare does frequently to remind us of the stakes (“Never alone/ Did the king sigh, but with a general groan,” as Rosencrantz says later). But with the addition of “buried,” it muddies the figure of speech. “Denmark” the man is buried, true; but to suggest that “Denmark” the country is likewise entombed? That slip of the tongue might be the first nationwide use of the play’s “corruption/decomposition” motif — a motif we’ll call the “something rotten” thread.
Finally, Horatio ends his undiplomatic overture with a double whammy: not only does he “charge” the Ghost-King to speak, but he also adds a heavenly oath. If Horatio does doubt the veracity of the Ghost, he knows that the alternative is likely a devil in disguise, so why does he risk offending the Devil by charging him “By heaven”? It could be an unconscious choice on Horatio’s part. But I wonder, despite the urgent repetition he’ll deliver in two lines’ time, if Horatio might be quite happy to chase the Ghost-Devil away with angry words and talk of heaven? It would, at the very least, save him the trouble of exercising his rusty Latin skills.
Quartos vs. Folio: In Q1 and F, Marcellus’s line is “Question it, Horatio,” whereas in Q2 it is “Speak to it, Horatio.” Normally, when a line appears in more than one version, it is considered correct. Additionally, it’s easy to see how “Speak to it” could be a compositor’s error, since it is a partial repetition of Marcellus’s last line. But I like the repetition, which adds a frantic urgency to the scene, and suggests that Marcellus is just barely holding his nerves together.
To Tweak or Not to Tweak: Some of the words I’ve discussed above — “usurp’st” and “the majesty of buried Denmark” — are going to cause problems to the modern ear. In addition, the syntax of lines 45-48 is a bit convoluted. As a potential simplification, you could snip out the indirect object:
What art thou that usurps this time of night
Together with the form of buried Denmark?
But the swiftest approach to Horatio’s lines would probably be:
What art thou that usurps this time of night?
By heaven, I charge thee, speak!
This approach obscures Horatio’s dubiousness, plus we lose the “something rotten” synedoche. But we’ll get plenty of both in scenes to come.