Originally Posted by
some imdb stuff
A deleted scene was shot where Imam, the wise man translating the markings on the headpiece of the Staff of Ra also translates another set of markings, which gives a warning about not looking into the Ark. Since this scene is not in the movie, it is a little confusing as to how Indy knew that he could only survive the opening of the Ark by closing his eyes. Perhaps he simply remembered the picture of the Ark he showed to the army officers; in it, an entire army is decimated, but the people carrying the Ark remain unaffected. So he may have concluded that opening the Ark is not necessarily deadly to anyone in close proximity, and that it is the visual contact that was deadly. Another option is that he remembered a relevant passage from the Bible (1 Samuel 6:19), where God "smote" the men of Beth Shemesh for looking into the Ark. Plus, there's a brief moment when Marcus Brody says the light from the Ark could lay waste to everything it touched, further warning of the Ark's power.