Albert Schweitzer, the great humanitarian and physician, elegantly described in two sentences, the nature of pain, and the obligation and the privilege, of the physician to relieve it, when he said: "We must all die. But that I can save him from days of torture, that is what I feel is my great ever-new privilege. Pain is a more terrible lord of mankind than even death itself".

Today as then, proper management of pain remains one of the most important and most pressing issues of society in general and of the scientific community and health professional in particular. Acute and chronic pain afflicts millions upon millions of persons annually, and in many patients with chronic pain and a significant percentage of those with acute pain, it is inadequately relieved. Consequently pain is the most frequent cause of suffering and disability and seriously impairs the quality of life of millions of people throughout the world. Studies suggest that annually in the United States and many other industrialized nations, 15 to 20% of the population has acute pain, and between 25 and 30% have chronic pain. In most instances acute painful disorders are correctly diagnosed and effectively treated, but there is impressive evidence that all too many patients with sever or very sever postoperative and post-traumatic pain, and sever visceral pain are not effectively relieved. In addition to needless suffering, in many patients unrelieved acute pain and perhaps the underlying pathophysiology cause it to progress to chronic pain. Of the patients with chronic pain half to two-thirds are either partially or totally disabled for periods of days, some for weeks and months, and some permanently. Because pain impairs one's ability to carry out a productive life, pain in general and chronic pain in particular is a serious economic problem as well as a major health problem.

Pain has been a major concern of humankind since our beginnings. Indeed it is even older, for there is reason to believe that pain is inherent in any life linked with consciousness. Certainly there is evidence that man has been afflicted with this evil since his beginning, for as the records of every race are examined, one finds testimonials to the omnipresence of pain. Prayers, exorcisms, and incantations bearing testimony to the prevalence and scourge of pain are found on Babylonian clay tablets, in papyrus, written in the days of the pyramid builders, in Persian leathern documents, inscriptions from Mycenae, and on the parchment rolls of Troy. Such records continue down through the ages in every civilization and every culture. The French surgeon Daetigus wrote: "Were we to imagine ourselves suspended in timeless space, over an abyss, out of which the sounds of revolving earth rose to our ears, we would hear naught but an elemental roar of pain, uttered as with one voice by suffering mankind".