Dr. Rheingold's paper makes a number of important points that deserve comment and re-emphasis. The four principles she has presented certainly represent the basic generalizations of behavior of all mammals as well as of the human species. The first principle-that infants respond to social stimulation-is scarcely novel in its own right, but what is particularly interesting is the paucity of detail with which she is able to document it. The lack is not hers but science's. It is astonishing to recall that the Babylonians and, a millennium after, the Egyptians, made such precise and detailed records of the stars that, thousands of years later, the more theoretically oriented astronomers of the Renaissance could utilize the data in the formulation of exact laws about the movements of the heavenly bodies. There is nothing anywhere in the history of our knowledge about human beings that corresponds to those precise observations. What little we know of the reactivity of the human infant has been learned within the last few decades. Man's interest in Man as an object of empirical observation is very recent indeed. One can hope that the documentation of this first principle will improve radically in the next half century. Dr. Rheingold's second principle-that the infant is active in the control of his environment-is a persuasive statement of a fact that has been too long neglected. I suspect that, in some curious fashion, John Locke was responsible for the failure of child psychologists to recognize the importance of this principle. The inherent passivity of his conception of the tabula rasa seems to have become converted into a similar immobility of action when the Lockian notion of the association of ideas was translated into the association of stimuli and responses. It is high time we recognized that, in infancy as well as in all other stages of development, the organism demands stimulation and manipulates the environment to secure it. The third and fourth principles, which concern the modifiability of the infant's social behavior and the corresponding modification of his social environment, represent the first steps in recognizing the major problem we have in developing a systematic view of the process by which socialization