# Sacred Geometry in 3D

So far we’ve been working in 2 dimensions, as if on a piece of paper, for the most part. But sacred geometry can be carried to the solid world of 3 dimensions. We’ve already seen that the major 2-dimensional shapes all have 3D analogs: **sphere **for the circle, **tetrahedron **(4 sides) for the triangle, hexahedron a.k.a. the **cube **(6 sides) for the square, and **dodecahedron **(12 sides) for the pentagon.

Using identical regular polygons, there are only 5 regular solids (or, to use the mathematical term, convex polyhedra) one can construct:

…the **octahedron **(8 triangular sides; like 2 pyramids joined at the base)…

…and the **icosahedron **(from triangles again, but with 20 sides).

These are called the **Platonic solids**, because Plato assigned each one to an element: the tetrahedron to **fire**, the cube to **earth**, the octahedron to **air**, the icosahedron to **water**, and the dodecahedron to the **astral**.

Next–Sacred Geometry in Personal Practice

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