In Polonius's house: Laertes, Ophelia, the warning

Polonius's house, the morning after the watch on the wall. Laertes is leaving for Paris and is saying goodbye to his sister Ophelia. He warns her about Hamlet. The prince's affections, he says, are sincere but not to be trusted: princes do not get to choose their wives; the choice belongs to the state. Hamlet's "favors" toward her are likely "a violet in the youth of primy nature" — sweet, brief, soon withered. She must guard her honor accordingly.

Polonius arrives. He has come to bless Laertes off and unloads, in the process, the most quoted body of fatherly advice in Shakespeare: "Give every man thy ear, but few thy voice." "Neither a borrower nor a lender be." "This above all: to thine own self be true." Polonius is a comic figure here — the speech is too long, too polished, too pleased with itself — but Shakespeare allows the lines themselves to be wise. Laertes accepts them with patience and goes.

Polonius then turns on Ophelia. What did your brother just say to you, he asks. He extracts the warning from her and intensifies it. She must not see Hamlet alone again; she must not "give words or talk with the Lord Hamlet." When she protests that he has spoken honorably, Polonius dismisses her — "you do not understand yourself so clearly as it behooves my daughter and your honor." She must obey. She agrees: "I shall obey, my lord." It is one of the most painful moments in the play. Ophelia has had no agency in any of the conversation; she is being moved like a piece on a board between her brother and her father, and the play has just shown how completely she is willing to be moved.