It was a rainy summer day and my wife Kate and I were flipping through the options available on HBO. We got to the ‘E’ section and stopped. We turned our heads toward each other and smiled. Kate had never seen The Exorcist and I hadn’t seen it in almost a decade. It was time.

William Friedkin could have left much of this movie on the cutting room floor. However, it is this inclusion of extraneous immaterial that lends itself to the sense of undressed reality and gravity most horror films don’t take the time to achieve.

In the opening scene, we observe Father Merrin (Max von Sydow) excavating an ancient ruin in Iraq. The lengthy sequence could have been boiled down to 2 or 3 key moments, but instead it feels like we spend an entire day with him. The effect it has is hard to describe, but powerful — almost hypnotizing. Eventually, we start to wonder who this man is and why we are spending all this time with him; He must be important, right? Then we leave him, and not just for a few scenes, but for nearly the entire movie. But, in the iconic climax of the film, when Father Merrin is called back into action to do battle with the demon, it all pays off.

In contrast, what I believe to be one of the most shocking moments in the history of the genre was originally left on the cutting room floor. I had been telling Kate about the infamous spider walk down the stairs scene for years. What I didn’t know was that we happened to be watching the original version, which had omitted the scene because the wires were visible before being digitally removed in the 2000 DVD release.

Friedkin’s Catholic horror masterpiece holds up, even without the spider walk. It is an example of how good horror is done: it takes itself seriously, it takes its time, and its images haunt you long after it’s over.