Unreason sometimes appears impregnable. But, just as the hardest of rocks ultimately get worn down by wind and weather, so does every castle of superstition and irrationality crumble before the ceaseless battering by science and reason. Say what you will and think what you want, but science shows the human body comprises interchangeable parts, each made of atoms and molecules in a complex arrangement. That’s just a fact of life; one that could help save your life.