"Tarkovsky is the greatest of them all. He moves with such naturalness in the room of dreams. He doesn't explain. What should he explain anyhow?" Thus Ingmar Bergman, in his autobiography The Magic Lantern, bows down before the Russian director while also hinting at what makes Tarkovsky's work so awkward to critics: it can verge on the inscrutable. Too opaque to yield concrete meaning, it offers itself as sacral art, demanding a rapt, and even religious, response from its audiences.