The play by William Shakespeare which has the quote: "Then must you speak of one that loved not wisely, but too well" is "Othello". These are words which are directly found in "Othello" in Act 5, scene 2, 354–367.

The quote is part of Othello's swan song. It is his attempt, before killing himself, to justify having suffocated his somewhat blameless wife Desdemona. Scholars point out that the solidity of the quote reveals one side of Othello's personality (the calm, cool, and collected). Still, the fact that Othello seems to have recovered from the jealous passion that drove him to murder his wife doesn't ensure any real credibility on his part. Some people, pitying the Moor's anguish, wish to accept his self-judgment—that he may not have loved in the wisest fashion, but he loved very deeply, and that is the reason he acted "in the extreme" by groundless charges against Desdemona.

Others (historians, scholars, etc.) unable to forgive Othello's rash, brutal, and overconfident act, find his justification just another self-delusion. In fact, Othello has shown himself extremely susceptible to jealousy. And it is difficult to accept that his foolish credulousness is compatible with loving his wife too well. He never gave her the benefit of the doubt or any real chance to defend herself.

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