Lie low
I'm Antonio. I'm Leonato's brother and friend. I don't have a big role to play, but I comfort my bro when he needs me the most. I offer sound advice to the guy when he's a mess. And you know what I think?
If he could right himself with quarreling,
Some of us would lie low. (5.1.51-52)
Who Said It and Where
Claudio loves Hero. Hero loves Claudio. The only problem is not everyone wants them together. The evil Don John tears them apart by bad-mouthing Hero all over town. He claims she's gone and done the nasty with another guy while she was engaged to Claudio. Total scandal.
The couple breaks up, but, since the rumors aren't true, Hero's cousin Beatrice and her crush Benedick come up with a plan to clear Hero's good name. They spread a rumor that she's died so Don John and his buddies can have a good, long think about what they've done to an innocent girl.
Meanwhile, Antonio confronts his grieving brother (and Hero's dad), Leonato, and pleads with him not to be so suicidal. That doesn't solve anything. Leonato claims Antonio can say nothing to make him happy again. Leonato will only calm down if told to by a man who has gone through the same kind of suffering. Where is Antonio supposed to find one of those?
Leonato says that folks who have it good know exactly how to fix other people's bad situations. Still, when the best advice-givers fall into a bad way, they, too, give in to irrational frenzies of suffering. What's the point of all this philosophizing? Well, we think it's just Leonato's way of justified his crying. After all, even philosophers, for all their philosophizing, whine when they have a toothache.
Antonio points out that Leonato's suffering is totally warranted. Instead of internalizing all of the suffering, though, it's only right he should share his suffering around, especially with the people that are the source of his grieving. Translation: go beat Hero's accusers to a pulp.
Leonato says it's time to let everybody know that Hero was innocent, especially Claudio, Don Pedro, and Don John. When Claudio and Don Pedro wander onto the scene, Leonato tries to pick a fight with the younger men, but they claim to be in a hurry to go somewhere. Then Antonio says if Leonato fights with them, they would lie low.