Last night I watched The Passion of the Christ for the first time - though I have watched it at least twenty times before. Film is like that sometimes. It was the same for when I watched Hitchcock's Rear Window and Psycho, having seen both numerous times before, and then watching them after not viewing them for some time. I think it has to do with more than Chesterton's maxim:
"...if you look at a thing 999 times, you are perfectly safe, but if you look at it the thousandth time, you are in frightful danger of seeing it for the first time."
For we are not simply talking about "a thing" when we talk about a film, but a number of things - images - relaying in sequence before your eyes; relaying mechanically, so that there is, for want of a better word, a voyeuristic element to it. That is to say, your eyes are taking in material before the retrospective brain can catch up. Alfred Hitchcock knew this well about film, and not incidentally many of his films pursue that very theme: the voyeur; and the getting caught up in something that you cannot control and which puts you and others in extreme danger or in a vulnerable spot, very often in part due to the fault of the one who looks where he ought not to look.
This element of film is also one of the reasons that Andrei Tarkovsky was so adamant (in his book Sculpting in Time and elsewhere) on how necessary it was for the filmmaker to recognize how huge a responsibility he had. Tarkovsky stressed the need for this responsibility to what some would call an exaggerated, blowhard, overbearing stance. But Tarkovsky saw. He knew, and said as much, that film was, in itself, a lumbering mechanical beast; and as such it requires heroic, untiring, vigilant measures of continual threshing and taming.
The power of film is evidenced in this 'ever new' phenomenon, whereby one can return to a certain film (one that is well made) and see it again as though for the first time, or even better than the first time. For film is time. Tarkovsky said that is why people go to see movies. To regain lost time.
And we cannot approach and apprehend eternity except through time.