Harriet Anderson's performance is beyond brilliance. She has a very difficult role, but there seems not the hint of acting on her part. It is a role where the character seems to be acting and is having a very rough time. Her performance is transparent and haunting. I saw this film most recently a few years ago (and have seen many movies since then), but i still recall vividly three of her scenes. The photography is magical and while not as praised as Wild Strawberries, Persona or Winter Light ( and a few other Bergman classics), its power and its passion reach inside your soul and dares you to resist living the story and the characters of the film. Also, Max von Sydow is brilliant as usual--he is certainly the most underrated actor of all time--theater, television or cinema. I highly recommend this film and then your viewing t he 1971 Passion of Anna, also with Max v.S. and a performance by Liv Ullmann that rivals Harriet's in Thtorug a Glass Darkly. The theme of Darkly is the human predicament in a world of suffering and illness. How does man survive if he actually "lives" his/her life, rather than just sports through life without any experience of art and the spiritual (good or bad). This film is part of a loose trilogy that includes the magnificent Winter Light and The Silence, though each can be viewed separately with no loss of discovery and enjoyment. When I was in college at UCLA from 1968-75 (under and grad school), Bergman was the rage with many people. He seems to be lost in the mists of time. But if go back and watch his films from the late 50's to the 70's, you will see cinema at its boldest and its greatest. Buy the films or rent them (Netflix has a good collection.). Darkly will shake your world and cause ripples of thought and feelings that move for a long, long time inside your mind, and if your fortunate your soul.. See this film.