Alas, thrice-gentle Cassio!
My advocation is not now in tune;
My lord is not my lord; nor should I know him,
Were he in favour as in humour alter’d.

– William Shakespeare

Othello, Act 3, Scene 4. Desdemona, shaken after Othello’s anger towards her, says this to Cassio. She uses a metaphor to compare her failed attempts to advocate on behalf of Cassio to a musical instrument out of tune. Othello is not himself, she explains, and if his physical appearance had changed as much as his personality she would not recognize him. Desdemona realizes that there are two Othellos, the kind and loving one she married and the angry one now who is not making sense. Othello appears to have developed a split personality after Iago poisoned his mind and turned him into a different person.