Why does montag not open the curtains in his house?

Montag does not open the curtains in his house because he is living in a society where books are banned, and knowledge is suppressed. Opening the curtains could potentially draw attention to his illegal activities, such as reading books, which could lead to severe consequences. By keeping the curtains closed, Montag is trying to maintain a sense of privacy and conceal his rebellious actions from the watchful eyes of the authorities.