In the 1960s, Rousas John Rushdoony began to advocate homeschooling, which he saw as a way to combat the intentionally secular nature of the public school system in the United States. He vigorously attacked progressive school reformers such as Horace Mann and John Dewey, and argued for the dismantling of the state's influence in education in three works: Intellectual Schizophrenia, a general and concise study of education, The Messianic Character of American Education, a history and castigation of public education in the U.S., and The Philosophy of the Christian Curriculum, a parent-oriented pedagogical statement. Rushdoony was frequently called as an expert witness by the Home School Legal Defense Association (HSLDA) in court cases.