William Morton's demonstration of the use of ether in 1846 was powerful in part because the patient had no memory of the procedure; nowadays, patients expect to have amnesia with general anesthesia. But conscious awareness — the ability to remember and explicitly recall events that transpire during surgery — still occurs on occasion, sometimes with devastating psychological consequences. The easy explanation is that awareness is due to underdosing of the anesthetic agent. This explanation provides a sense of control and a ready fix (administer more anesthesia) but conveniently overlooks a secret: the state of consciousness is typically not monitored directly . . .