Inherent in man's biologic endowment is the need for homeostasis and the equipment for its maintenance. Assaults upon and threats to his physical and emotional integrity which upset this homeostasis provoke adaptive reactions intended to restore the equilibrium within the internal milieu of the body, and between the body's internal and external environment. Such reactions to life stress usually are manifested as alterations in behavior which may vary widely in degree, content, duration, and effectiveness. When sustained these reactions may be productive of discomfort and impairment of tissue integrity. Many of the illnesses experienced by man, then, may occur in large part as a byproduct of his attempts at adaptation.Abstract Teaser