the question about time and circles is interesting... i know i have heard theories of time being cyclical or circular. for example, terence mckenna's timewave zero theory holds that time moves in a spiral as a fractal. the spiral is made up of circles that get smaller and smaller, like a string being wrapped around a cone. each point on any of the circles corresponds to points on the larger and smaller circles and resonates with them, so time is repeating itself but at a faster and faster rate. this would explain why time seems to be speeding up and cultural advancement is happening faster and faster.
here's a link to a good explanation of the theory if you've never heard and are interested.
http://www.youtube.com/watch?v=vtnV25LWFQ8