ABSTRACT
Pain research earns a distinctive niche for several reasons, but none more persuasive than its practical importance in human welfare, for pain is the most common clinical complaint and the pervasive source of much suffering. Pain provides an essential mechanism for protecting organisms from destructive influences and those rare cases of congenital insensitivity to pain are susceptible to a variety of harmful events that usually curtail the longevity of those unfortunate individuals. Thus, pain cannot be regarded as less useful or desirable than vision or any other sense, for it is of key importance in sustaining life. Yet it must be considered quite separately from other sensory systems because its key role is not that of exploration, but rather to guide warning and avoidance behavior. Indeed, pain is a reaction that frequently defies description in terms of a given stimulus condition and thus requires precise definition that is not obfuscated by the important subjective issues of suffering.
