Although it is not his most famous soliloquy from the play, Hamlet’s ‘’Tis now the very witching time of night’ speech, which brings Act 3 Scene 2 to a close, is notable for the imagery Hamlet uses as he prepares to go and speak to his mother, Gertrude. Indeed, as the very phrase ‘witching time of night’ suggests, this speech is one of the reasons Hamlet is so often considered a ‘Gothic’ play, along with its castle setting, its Ghost, and its dark secret threatening to tear the family and kingdom apart.
Let us go through this most Gothic of speeches from Hamlet, offering a summary and analysis of its meaning as we go. (We have analysed the play as a whole here.)
’Tis now the very witching time of night
When churchyards yawn and hell itself breathes out
Contagion to this world. Now could I drink hot blood
And do such bitter business as the day
Would quake to look on. Soft, now to my mother.
Everyone else, including Polonius (the last to leave), has now left the stage, with only Hamlet remaining.
’Tis now the very witching time of night
When churchyards yawn and hell itself breathes out
Contagion to this world.
He reflects that it is now the hour appropriate for witchcraft: in some performances, Hamlet’s statement may be preceded by the sound of a bell striking (another nice Gothic touch). It’s late.
It’s the time of night when graveyards yawn open like mouths and the foul stench of hell seeps out, like bad breath from a mouth (indeed, worse: ‘Contagion’ suggests pestilence, and it’s worth remembering that the Elizabethan playhouses 
were periodically shut during outbreaks of the bubonic plague). Some editions of the play have ‘breaks’ instead of ‘breathes’ (or ‘breaths’, as it appears in the First Folio printing of the play from 1623), but ‘breathes out contagion’ probably makes more sense than ‘breaks out contagion’.
Nevertheless, it is worth noting the collapse of the boundary between this world and the next: a common theme of Hamlet, as the appearance of the Ghost (trapped in Purgatory, assuming it isn’t some demon sent from hell itself) makes clear, along with Hamlet’s numerous speeches (such as his talk of the afterlife as the ‘undiscovered country, from whose bourn / No traveller returns’). And hell breathing (or breaking) out into ‘this world’ is another such example of hell/heaven/purgatory encroaching upon Hamlet’s own world. Fittingly, the appearance of the Ghost seems to have infected (like that contagion!) his thoughts with ideas of hell and what happens after we die.
Now could I drink hot blood
And do such bitter business as the day
Would quake to look on.
Hamlet declares that, at such a time as this, he could drink hot blood: something witches were said to do. Whether he is saying he has an appetite for such a thing (‘now could I quite happily gulp down some hot blood and enjoy it’) or expressing disgust (‘now I am so fed up that I could drunk hot blood’) is ambiguous, however.
He goes on to say that he could commit such awful deeds that, even in broad daylight (rather than the current ‘witching time’ of darkness and night), people would shudder to see him doing such things. (The First Folio has ‘bitter business as the day’, but the Second Quarto has ‘business as the bitter day’, where it’s the day, rather than what Hamlet gets up to, that’s terrible and bitter; but it seems to make more sense, especially following his talk of guzzling down hot blood, to attribute the bitterness to Hamlet’s activities rather than the daytime.)
Soft, now to my mother.
But although he could do these things, he hasn’t got time, because he has to go and see his mother, Gertrude.
O heart, lose not thy nature. Let not ever
The soul of Nero enter this firm bosom –
Hamlet tells his heart not to betray his natural feelings: that is, his sense of loyalty and love towards his mother as his flesh and blood. Nero, the Roman emperor, had his own mother, Agrippina, killed, but Hamlet doesn’t want to treat his mother so harshly.
Curiously, as Ann Thompson and Neil Taylor point out in their notes to Hamlet: Revised Edition (The Arden Shakespeare Third Series), Agrippina was accused of poisoning her husband and sleeping with her brother, which makes the Nero reference even more significant: after all, Hamlet cannot be sure that Gertrude wasn’t complicit in Claudius’ poisoning of her husband, King Hamlet. And Claudius, in being her dead husband’s brother, was legally her brother (technically, brother-in-law), too. So the Nero parallel is suggestive of what’s going on in Hamlet’s mind.
Let me be cruel, not unnatural:
I will speak daggers to her but use none.
My tongue and soul in this be hypocrites.
Hamlet resolves to be cruel to his mother, but not unnatural: what does he mean? Thompson and Taylor, in their gloss on this line, suggest that we view this line in light of the following one: Hamlet intends to speak sharply to his mother (as sharp as daggers), but not actually commit violence against her (‘but use none’). So he seems to be saying that he will speak cruelly to his mother, but not act unnaturally or inhumanly by striking her physically.
However, as the next line shows (‘My tongue and soul in this be hypocrites’), he appears to want to commit physical harm against his mother, so angry has she made him. His soul wants to harm her, but his tongue will merely speak harsh words to her, so he will be behaving hypocritically.
How in my words somever she be shent
To give them seals never my soul consent.
In other words, ‘however I use my words to rebuke or scold my mother, my soul does not consent to act upon them by harming her’ (e.g., if in the heat of the moment he threatened to strike her, he would never actually do such a thing). ‘Shent’, by the way, is the past tense of the obscure archaic verb ‘shend’, meaning ‘rebuke’.
And that concludes Hamlet’s ‘witching time’ speech and, with it, Act 3 Scene 2. The next scene will not involve Hamlet, but Act 3 Scene 4 will be the famous bedchamber scene between him and his mother, Gertrude, in which he will indeed be cruel, but ‘only to be kind’. In uttering those words, Shakespeare appears to have coined a phrase that is still with us: ‘cruel to be kind’.