Naturalism is a philosophy of education that believes ultimate reality lies in nature, not the supernatural. It views the universe as governed by natural laws and subordinates mind to matter. Jean-Jacques Rousseau was a prominent advocate, arguing that education should follow a child's natural development rather than rely on schools and books. Naturalism aims for a child's complete living and development through self-expression, adjusting to their environment, and developing their personality through natural growth and culture. The teacher guides this natural development by setting the stage and protecting children's freedom and spontaneity.