Plato taught that existence is dominated by form, and that the five regular polyhedrons known to mathematicians _ the 4-sided tetrahedron, the 6-sided cube, the 8-sided octahedron, the 12-sided dodecahedron and the 20-sided icosahedron _ have symbolic significance . ( A regular polyhedron is a three-dimensional form whose faces are all regular polygons; the cube, for example, is made up of 6 regular polygons called squares .)
