What would you say about a woman who, despite stroke-induced paralysis crippling the entire left side of her body, insists that she is whole and strong--who even sees her left hand reach out to grasp objects? Freud called it "denial"; neurologists call it "anosognosia." However it may be labeled, this phenomenon and others like it allow us peeks into other mental worlds and afford us considerable insight into our own. The writings of Oliver Sacks and others have shown us that we can learn much about ourselves by looking closely at the deficits shown by people with neurological problems. V.S. Ramachandran has seen countless patients suffering from anosognosia, phantom limb pain, blindsight, and other "disorders,"