First, what does Pestalozzi understand by the “natural” development? “There is an impulse in every capacity of human nature, which compels its development from lifeless inactivity into a developed power” (1: p. 738). This impulse leads each one of our powers to a spontaneous activity or exercise, and Nature develops it by “the single method of its own activity.” This natural, organic unfolding of life, with its multiple activities, is necessarily harmonious when unhindered by human artifices or unfavorable environment. We must guard this natural harmony of human nature, upon which the peace and happiness of our individual and social life rest. “No one faculty in the human child must be treated with exclusive or indiscriminate attention, for their co-agency alone can ensure a successful development of the whole being.” “Every one-sided development of our powers is untrue and unnatural; it is only apparent cultivation, ... and not human culture itself” (1: pp. 736, 737). Pestalozzi is not only antagonistic to that kind of education which “has an external, limited end of culture, of morality, of social efficiency in view, and wants to fit the child to this,” but he opposes that type of pedagogue who requires the child to conform to a plasterlike model of a perfected man. Each particular child is always the end, the object, the standard. “Whatever, therefore, man may attempt to do by his tuition, he can do no more than assist in the effort which the child makes for his own development. To do this so that the impressions made upon him may always be commensurate to the growth and character of the faculties already unfolded, and at the same time, in harmony with them, is the great secret of education. The knowledge to which the child is to be led by instruction must, therefore, necessarily be subjected to a certain order of succession, the beginning of which must be adapted to the first unfolding of his powers, and the progress kept exactly parallel to that of his development” (11: p. 611). This method of leading or assisting the child along the course of his successive developmental stages in a natural, progressive order is what he terms “psychologizing education,” and this was the central problem of his whole experimentation, so far as the individual child was concerned. The discovery of his famous “Method of Elementary Instruction” was the fruit of his lifelong endeavor toward this end, but he considered his achievement only as a beginning.