Godel’s incompleteness theorem is not only accepted mathematics, but the first theorem to be subjected to formal proof by means of a computer. The theorem says that maybe 2 + 2 is not always 4, which is hard for many mathematicians to swallow (google “Is Arithmetic Consistent?”), and the reason arithmetic may contain some contradictions is the axiom of extension, the method of proof used to demonstrate that the finite case implies all cases.
I’ve been studying a couple of illustrations Apech turned me onto–from the temples in Egypt, a long time ago. You might find this useful, with regard to the sacrum and L5:
I’m writing lately about proprioception and sitting the lotus; I write for myself, first and foremost, but I’m hoping this approach will also serve for Westerners who want to learn to sit the lotus. I don’t sit many sesshins, and I don’t care if my sitting is ten minutes or 50; maybe I average about 30. It’s about stretch, but it’s also about subtle activity that takes place because of the stretch in the ligaments and fascia. These tissues can generate nerve impulses to contract muscles to relieve stretch, and in the lotus there’s a constant reciprocal stretch and activity.