With space and time, there is Universe. Universe exist with the compostion of space and time. Space has many shapes and features but are all able to be viewed with our eyes.

Time however can not be either can be touched or seen. The only thing we can know about time is that time flows within same cycle. One day is 24 hours, never been 25 hours or 23 hours.

Time has been flowing with its own cycle since, the birth of the Universe. and this unchangeable cycle of time serves for the unchangeable order of the various features and shapes of space.

Then, can time be observed through the eye of man's wisdom?

Yes, it can. Time is invisible but from the change of the space, we are able to trace back the footprints of the time. and there are two typical ways to prove it. That is the cycle of a day and an year.

A day is the change of day and night. When the time of day ends, the time of night starts.

When the time of night ends, the time of day starts. and also season changes through circulating just like day and night.

With this understanding of the cycle of circulation, in the far east culture, sexagenary cycle has been used until nowadays.

The Gregorian calendar, the current calender, is based on the linear time thinking. This might be the difference of the West and East thinking of Time.

But Time never stops. Instead it is eternal. Therefor this world is eternal. The circle is the shape of movement of the circulation of Time.