Heard this from a metaphysics loving maths grad once.

1 is unity, the oneness of all creation
2 is duality, the separation of opposites
3 is simplicity, three points defining a circle
5 is complexity, when all hell breaks loose mathematically
7 is completeness, the limit of items in a typical short term memory
11 is transcendence, if you can inuitively grasp 11 without using arithmetic, you mind will go beyond.

He drew me a diagram with numbers in all sorts of weird arrangements, with seemingly logical explanations for why the go where they do, including pi, infinity and other stuff. Anybody get where he's coming from?