Dreyer is best remembered today for his 1928 classic THE PASSION OF JOAN OF ARC. It's an amazing, intense experience quite unlike any other I can think of, but it's only one of the films that I love from the director. The 1943 DAY OF WRATH is a powerful witch-buring parable made under the noses of the Nazis. My favorite of his films might well be 1955's ORDET, about two pious families with differing religious beliefs. These films contain depths that my paltry summations don't even begin to touch. They are meditations on belief, disbelief, and the way individual human psychology informs and malforms religious dogma. They're not for everyone, but I love them.
I bring up Dreyer here to point the way toward an excellent website dealing with his life and work. Carl Th. Dreyer is a first rate resource for anyone interested in this invaluable artist--it provides articles, biographical research, and much more. I wish that every artist I love had such an impressive website. Go check it out.