You're in a desert walking along in the sand when all of the sudden you look down, and you see a tortoise, it's crawling toward you. You reach down, you flip the tortoise over on it's back. The tortoise lays on it's back, it's belly baking in the hot sun, beating it's legs trying to turn it'self over, but it can't, not without your help. But you're not helping. Why is that?