The theme is probably that people have to believe in something, (in this case reality,) in order to survive. Hitcock's p.o.v. on how that when something is not in sight, then you can't prove it is really there, seems like a babies p.o.v. For ex., when a babies mom goes around a corner or leaves the room it might cry and cry until the mother is back and holding it. Even if the mom is in sight, but not holding the baby, then it will still cry.