advolution
n. a rolling toward

“The ball was my idea,” said Steven Spielberg of the boulder that threatens Indiana Jones at the start of Raiders of the Lost Ark. “I don’t even know where I came up with it — it might have been deeply in my subconscious from something I saw when I was a kid — but I just said, ‘You know, at some point some huge boulder should start chasing Indy, and it almost squashes him three or four times until he gets out of the cave.'”

The scene was shot 10 times, with the crew replacing fallen stalactites each time. “I didn’t know it was gonna look as good as it did until the day [production designer] Norman Reynolds showed me that he had actually made a boulder that was something like 22 feet in circumference,” Spielberg said. “So I didn’t have Harrison step in the shot until I was completely convinced it was safe. Once we’d rehearsed it several times with a stuntman, Harrison did every shot himself.”

When Spielberg, George Lucas, and screenwriter Lawrence Kasdan had met in January 1978 to brainstorm ideas, it was quickly clear that Lucas already had an articulate vision of the story. At one point Kasdan asked Lucas why he didn’t direct the film himself. He said, “Because then I’d never get to see it.”

(From J.W. Rinzler, The Complete Making of Indiana Jones, 2008.)