Some years ago, I heard an arbitration case involving the mistreatment of a patient in a mental hospital. The patient had an uncontrollable desire to drink water, a condition called polydipsia. The switch in the brain that was supposed to trip when he'd had enough liquid was stuck in the "on" position. He would drink water from any source -- a toilet was as good as a sink -- and if no one stopped him, he would keep drinking until his body fluids were so diluted he passed out.

As I attempt to digest my Thanksgiving dinner, I've been thinking about that guy and how he is a metaphor for all of us: Our "enoughness" switch is broken.

The most recent example from Wall Street is the case of Raj Rajaratnam. He's the hedge-fund billionaire who was arrested and charged with insider trading. Brokers have always enjoyed having a little edge over the competition. Or, as Roy Blount Jr. put it, "If it ain't fixed, don't broke it." But a billionaire is a person with a thousand million dollars. Why would a person with a thousand million dollars risk going to prison for a chance to make more money?

Avarice and conspicuous consumption are part of the problem, but the failure of enoughness is larger than that. There is also the delusional sense of power over the world. Anorexics have it. 'Roid heads have it. "There are no limits to how big (or little) I can get. I am in charge." The United States military has it. "There are no physical, logistical, political, financial or historical facts that can stop us. We can defeat evil."