of education at the University of Illinois, where he served as the Director of the School of Education from 1908 until 1917. He was a professor of education at Teachers College, Columbia, from 1917 to 1940. An opponent of pragmatism and progressive education, Bagley insisted on the value of knowledge for its own sake, not merely as an instrument, and he criticized his colleagues for their failure to emphasize systematic study of academic subjects. Bagley was a proponent of educational essentialism. A. S. Neill A. S. Neill founded Summerhill School, the oldest existing democratic school in Suffolk, England, in 1921. He wrote a number of books that now define much of contemporary democratic education philosophy. Neill believed that the happiness of the child should be the paramount consideration in decisions about the child's upbringing, and that this happiness grew from a sense of personal freedom. He felt that deprivation of this sense of freedom during childhood, and the consequent unhappiness experienced by the repressed child, was responsible for many of the psychological disorders of adulthood. Martin Heidegger Martin Heidegger's philosophizing about education was primarily related to higher education. He believed that teaching and research in the university should be unified and aim towards testing and interrogating the "ontological assumptions presuppositions which implicitly guide research in each domain of knowledge." Jean Piaget Jean Piaget was a Swiss developmental psychologist known for his epistemological studies with children. His theory of cognitive development and epistemological view are together called "genetic epistemology". Piaget placed great importance on the education of children. As the Director of the International Bureau of Education, he declared in 1934 that "only education is capable of saving our societies from possible collapse, whether violent, or gradual." Piaget created the International Centre for Genetic Epistemology in Geneva in 1955 and directed it until 1980. According to Ernst von Glasersfeld, Jean Piaget is "the great pioneer of the constructivist theory of knowing." Jean Piaget described himself as an epistemologist, interested in the process of the qualitative development of knowledge. As he says in the introduction of his book Genetic Epistemology (): "What the genetic epistemology proposes is discovering the roots of the different varieties of knowledge, since its elementary forms, following to the next levels, including also the scientific knowledge." Mortimer Jerome Adler Mortimer Jerome Adler was an American philosopher, educator, and popular author. As a philosopher he worked within the Aristotelian