Raba said: A person is obligated to be fragrant/intoxicated [with wine] on Purim until he does not know the difference between ‘Cursed is Haman’ and ‘Blessed is Mordecai’
Until he does not know
Knowledge in this case is connected to acknowledging something and recognizing it with one’s eyes. Understanding, though, is in the heart. It resists being grasped visually and is only understood via the heart, which draws its knowledge from the very source of the thing.
This is reference to the lots drawn in the Book of Esther. These lots are determined by fate, which refers to understanding, and this is…
A person is obligated…until he does not know
One is obligated to not know by means of consciousness and visual recognition, but rather from the understanding of the heart one must know Cursed is Haman and Blessed is Mordechai.
This explains the custom of switching clothes on Purim. Even without recognizing based on someone’s clothes, one can see the most base individual has the divine name manifest upon him, and thus one can truly peer into his untarnished soul.