Watch it as many times as you like. Study it. Analyze it. Dissect it. However many ways one approaches this scene — arguably the single most famous in cinema history — something about it defies explanation. Something about it, more than 50 years after it was shot, invests this awful scenario with a power out of all proportion to its constituent parts. Any discussion, meanwhile, has to start with the myriad elements that Hitchcock employed in order to depict what is, in the end, a drawn-out act of savagery — the murder of Marion Crane (Janet Leigh). Consider the suddenness of the attack; composer Bernard Herrmann’s violins and cellos screeching along with Marion’s shrieks of shock and fear; the seemingly manic — but, in fact, meticulously plotted — editing; Marion’s literally naked, and thus profoundly unnerving, vulnerability. Everything in this scene, which took seven days and more than 70 individual shots to complete, has been added to the mix with a single purpose in mind: to terrify. And it does. If one scene can be said to have changed the movies forever, the shower scene in Psycho is it.