How does Balram's encounter in the bookstore influence his actions in "The Sixth Night"?

Balram's discovery, in a bookstore run by a Muslim in the low-class, red-light district of Delhi, is of a quote from a work of poetry: “You were looking for the key for years / But the door was always open.” This quote haunts Balram and becomes the seed in his mind telling him to kill Mr. Ashok.