Butterfly in the opera. Like Pinkerton, Gallimard sees his conquest through the lens of orientalism. In this lens, Song, a singer with the Peking Opera, is mysterious and exotic. Orientalism was in part an outgrowth of western imperialism, in which Europeans and Americans forced their claims on Asia and believed that the people should also submit to westerners. To Gallimard, Song is a stereotype of the perfect submissive female who, like Madame Butterfly, is willing to sacrifice everything for her man. Gallimard says, "We, who are not handsome, nor brave, nor powerful, yet somehow believe, like Pinkerton, that we deserve a Butterfly" (Act I, Scene V). After the truth about Song is revealed, Gallimard understands that his own sense of inferiority and his need to feel handsome and brave by associating with a person he considers a submissive woman have led to his demise. Because he is so blinded by gender stereotypes about Asian women, Gallimard is essentially "mentally blind" and cannot see Song for what she really is--a man. 

Gallimard appears to be "mentally blind" in M. Butterfly because he can assert a sense of power in the fantasy world that he creates for himself.  In his regular life, Gallimard has little influence and cannot attract women into his company in the way that other men around him can.  As a result, Gallimard buys into the stereotypes associated with "Orientalism" and forces Song to interact with him according to his desires.  In this relationship, Gallimard feels a sense of power, control, dominance, and influence that he did not have in his previous life.  In order to continue in this role, Gallimard must be "mentally blind" to the reality of his situation.