The following anecdote from Andrei Tarkovsky: Interviews answers your question:
>One day, during a public debate organized after a screening the discussion dragged on and on. After midnight, a cleaning woman arrived to clean the screening room, wanting to throw us out. She had seen the film earlier and she didn’t understand why we were arguing for such a long time about The Mirror. She told us, “Everything is quite simple, someone fell ill and was afraid of dying. He remembered, all of a sudden, all the pain he’d inflicted on others, and he wanted to atone for it, to ask to be pardoned.” This simple woman had understood it all, she had grasped the repentance in the film.