Pythagorean world view. Diagram showing the elements of the Universe as espoused by Pythagorean philosophers and interpreted by 16th century Europeans. At centre is a set of triangles representing land, air and water, above these is a triangle representing the skies. Above this is the realm of God, Heaven. Below the land is the abyss contained by the inferno of Hell. This woodcut comes from 'De opere Dei creationis seu de mundo' by Helisaeus Roeslin, published at Frankfurt in 1597.