Description:

Plato was not only an outstanding philosopher, but also a mathematician. Above the entrance to his Academy, he placed the inscription:

"Let no one who does not know geometry enter here."

He believed that matter is made of perfect entities, which are geometric figures. The simplest of them is a triangle, which is an element of other polyhedra.

Equilateral triangles can form ideal solids: a tetrahedron, an octahedron, an icosahedron, and a cube from two triangles folded into a square. The combination of all elements is the dodecahedron, which is formed from regular pentagons.

All Platonic solids are a closed set of polyhedra.