Note to Twelfth Night, 3.1.139, "That you do think you are not what you are"

When Olivia asks Cesario/Viola what he/she thinks of her (the alluring Olivia, she is probably hoping), the ironic meaning of Cesario/Viola's answer is clear; although Olivia does not think that she is a woman in love with a woman, she is. However, it seems unlikely that Cesario/Viola means for Olivia to guess her sexual identity secret, so given that Cesario/Viola came as a messenger of love from Orsino, Olivia may take the line to mean "You think you are not one who could ever love Orsino, but you could." If this is the way that Olivia takes it, then her reply, "If I think so, I think the same of you," means "Maybe it's true that I'm not the woman who could never love Orsino, but I also think that you are not the man who could never love me."

Imogen Stubbs as Cesario/Viola, left and Helena Bonham Carter as Olivia, right—1996