The perfect shape of the circle has two important features: its strong dependence on the centre and the infinity of its outline. Therefore, it is no wonder that this shape is widely used in religious and philosophical contexts. And obviously a lot of architectural and mathematical problems couldn’t be solved without the magic that happens when a divine circle is drawn on a sheet of paper. Pythagoras knew that as well as Leonardo, and circles even came to relate to the economy when Kondratjew came up with his theory of economic cycles.