Hitchcock at his best. He combined four elements: The "eee-eee-eee-eee" sound, the knife going up, blood running into the drain and our imaginations. This struck at the fear and paranoia in millions of viewers. He once said something like. "When a person is on a rollercoaster, they can't figure out why in the world they're doing this. But, if they didn't feel like that during the ride, they would be disappointed when the ride was over." Until I saw it the second time, I didn't realize that he never actually showed the knife going in. Got me!
