I came yonder from a great supper: the prince your brother is royally entertained by Leonato: and I can give you intelligence of an intended marriage.
I just came from a big dinner: your brother, the prince, is being royally entertained by Leonato, and I can tell you about an upcoming marriage.
Borachio · Act 1, Scene 3
Borachio brings Don John gossip about Claudio's plans to marry Hero, offering him the raw material for his scheme. The line matters because it shows how quickly rumors travel and how easily a malcontent can turn information into a weapon. It reveals that in this world, knowledge is power, and those with nothing to lose are most dangerous.
Being entertained for a perfumer, as I was smoking a musty room, comes me the prince and Claudio, hand in hand in sad conference: I whipt me behind the arras; and there heard it agreed upon that the prince should woo Hero for himself, and having obtained her, give her to Count Claudio.
I was hired as a perfumer, and while I was smoking a musty room, the prince and Claudio came in, walking hand in hand, talking seriously: I hid behind the curtain; and there I overheard them agree that the prince should court Hero for himself, and once he won her, he would give her to Count Claudio.
Borachio · Act 1, Scene 3
Borachio reveals that he overheard Don Pedro and Claudio planning the wooing arrangement, and he will use this knowledge to stage a false seduction. The moment sticks because it shows how easily a servant can overturn the plans of princes by simply hiding and listening. It establishes that the play's central mechanism is overhearing—what you see and hear, not truth, will decide everyone's fate.
The poison of that lies in you to temper. Go you to the prince your brother; spare not to tell him that he hath wronged his honour in marrying the renowned Claudio--whose estimation do you mightily hold up--to a contaminated stale, such a one as Hero.
The damage is yours to control. Go to your brother the prince; don’t hesitate to tell him that he’s dishonoring himself by marrying the famous Claudio—whom you hold in high regard—to a tainted woman like Hero.
Borachio · Act 2, Scene 2
Borachio tells Don John exactly how to weaponize the false seduction: by poisoning the prince and Claudio's minds before showing them the proof. The line matters because it lays bare the strategy of the play's villainy—the poison is in the suggestion, not the evidence. It shows that once doubt is planted, the eyes will find proof for whatever the mind already believes.