A cosmogram is a flat geometric figure depicting a cosmology. Some of them were created for meditational purpose. Mandalas are the best known cosmograms, but similar diagrams, known as schema , were also used in western Europe during the Middle Ages.
Many cosmograms feature a circle and a square, or a circle and a cross. The circle may represent the universe, or unity. The square or cross may represent the Earth, the four directions. The centre may represent the individual. Many diagrams featuring circles and squares or crosses may be interpreted as cosmograms, although they may not be intentionally created as such. For example, traditional Chinese coins that are round with a square hole in the middle, have been given such an interpretation, and so has the board for the game ludo, see Cross and Circle game.