Homeostasis is a term in physiology to describe the maintenance of the internal viability of organisms within a prescribed range. The word homeostasis is derived from the Greek homeo, means “same,” while stasis means “stable;” thus, “remaining stable by staying the same.” Walter Cannon coined the term “homeostasis” from a related idea developed earlier by Claude Bernard. Claude Bernard declared “All the vital mechanisms have only one object, to preserve constant the condition of the internal environment.” Studies in physiology and medicine have interpreted that statement to mean certain aspects of the internal milieu are fixed at a specific set point. The historical concept of homeostasis is the basis of modern concepts of autonomic regulation and control. Organisms are always in a state of homeostasis, even during states of arousal, except during illness or disease. Also see allostasis.