Fear may very well be a caveman fear of the predator, of the giant lizard chasing them - maybe that's what Steven Spielberg connects with so well in Lost World.
Strange story about Degas. He hated women, didn't want to be with them. Yet he spent much of his life painting them. He had seen his father maltreat his mother, must have had a deep fear that he'd do the same thing.
Only when we are no longer afraid do we begin to live.