 He also believed each stage was imbued with a different "sphere" - the Moon (0-7 years old), Mercury (7-14 years old), and Venus (14-21 years old).Aside from these spiritual underpinnings, Steiner's seven-year stages are broadly similar to those later described by Jean Piaget.In other respects, Steiner's ideas are descended similarly from educational theories developed by Comenius and Pestalozzi.