I'm no student of sacred geometry - so don't all pounce on me at once - but it was my understanding that SG had something to do with all matter somehow being able to be reduced to one of 5 basic forms or solids (see Cusp's avatar), right down to our own DNA. (I've only read a little about this in the past, so I can't remember it all - but there's also the golden ratio thing that fits in there somehow.)

I think what's causing some contreversy here is that it was (for some reason) named "sacred" geometry - implying godlike or theism. But it may not necessarily be so. I think it just means that it's a basis or foundation to a much more complex 'world'. It's essentially what science is all about; getting down to the most fundamental principle of a theory. The ultimate being, the theory of everything (linking relativity with quantum physics).

So, whether you think it's 'sacred' or not, it is pretty convenient how the pieces fit together. Whether they solve any great mysteries about ourselves has yet to be proven.

Now, what's interesting is that this 'geometry' (at least the golden ratio) can also be applied to other things; like sound/music in the Circle of Fifths. Again, not 'sacred', but pretty cool!