Ask a person if, when carrying an uncooked egg in his breastpocket, wether that egg would protect his head when, say, being hit by a car, and that person would say that, of course, a raw egg in his pocket wouldn't, couldn't protect him. "Even if it broke?", you would ask. "Especially if it broke!", he would say. The idea that something as fragile and inherently breakable could somehow protect you from harm would be considered ludicrous.
Then ask him if that same egg could protect him from braindamage if you would ducttape it on top of his head. You will get the same negative answer. He'd probably shoot you an incredulous look as well as a few suggestive remarks about 'sympathetic magic'.
But ask him if he thinks a styrofoam helmet would protect him from getting braindamaged after being hit by a car and he will launch into descriptions of having fallen of his bike once and his helmet breaking and that this was proof, *proof* I tell you!, for the helmet's noggin'-safing abilities.