This drawing from Johannes Kepler’s 1619 book, Harmonice Mundi, illustrates the Platonic associations of the regular solids with the classical elements: The tetrahedron corresponds to fire, the octahedron to air, the cube to earth, the icosahedron to water, and the dodecahedron to the cosmos or ether:

This drawing from Johannes Kepler’s 1619 book, Harmonice Mundi, illustrates the Platonic associations of the regular solids with the classical elements: The tetrahedron corresponds to fire, the octahedron to air, the cube to earth, the icosahedron to water, and the dodecahedron to the cosmos or ether: