Check out this wonderfully wacky piece at Good Math, Bad Math on Rudolph Steiner and Theosophical Math. For example:
In normal projective geometry, there’s an interesting kind of duality, where you can take theorems involving lines and points and switch the lines and the points in the theorem, and the result is also a theorem. So, for example: given two distinct points, there is exactly one line that crosses through both of them. The dual statement of that is: given two distinct lines, there is exactly one distinct point that they both cross through.
Steiner insists on carrying duality to silliness, and that’s where the really crazy math comes in. Since there’s normal space where parallel lines converge and intersect at infinity, there must be a dual space where everything is at infinity, and things converge towards the finite.
Wow. Where can I get some of that stuff…?