A triangle is the simplest possible polygon.
Draw a triangle. Now put a point somewhere outside the triangle but close to it. Draw a line connecting the point to each vertex of the triangle.
You now have a two-dimensional representation of the simplest possible polyhedron, the tetrahedron. Two-dimensionally, with the sides transparent, it looks like a quadrilateral with an "X" through it.
Now follow this logic to make a two-dimensional representation of the simplest possible hyper-polyhedron, which I'm not sure if has a name but I'll call it a hyperpentahedron. It has five three-dimensional sides, just as a tetrahedron has four two-dimensional sides and a triangle has three one-dimensional sides. Put a point outside the tetrahedron but somewhere close to it. Draw a line connecting the point to each vertex of the tetrahedron.
OMG, it's a pentagram!
There you have it, mathematical proof that the fourth spatial dimension is evil and the devil resides there.