Nature and building blocks
Well, Erik Jurrien Knoops you should be careful what you ask for, some times there is a sword of Damacles over your head.
Beyond the mumbo jumbo, the spiritual connotations, these are the three basic building forms, found within nature, and found with in our movements. Only, most times they are referred to as sphere, rectangle, and triangle, the basic buiding blocks.
In reference to Aikido, we use the effiecientcy of these shapes to facilitate the practical movements needed to either move us, move our opponent, manipulate technques or objects within our movements.
I kind of thought that the simplicity of having you, the person who posed this question, find the shapes in practice would be a good starting point.
The rest of the drivel about the spiritual aspect is up to you, as all spiritual meaning is derived from nature, the universe, and the way humanity interacts/ understands their environment. Hence the same elemental events may be interpreted differently by different religions, and although they are the same exact event. We, humanity, have written our own meaning which explain event or thoughts in terms we can understand.
Circle, square, triangle? You must mean the Masonic Temple, eh? No? You really mean Aikido?
Then look to your practice, ask about how people have related the movements to these simple shapes, and the rest is up to you.
Hey, that guy is a sphere head ... that woman has a triangle problem, and that sensei is square, I mean he don't cut no corners, do he?
Really, kidding aside....there are so many ways to remember how to move, explain what you should remember to move, and then totally take them out of context into a religious manifestation ... just go do it to find the answer.
ERIK! Quick! Move! There is mouse gnawing at the string!
Boy, am I glad to be a peasant.