Why life never comes a full circle ?

Q: Does life has come a full circle?

A: If life could come a full circle we could time travel !

Life can never come a full circle as it has a linear relationship with time. The way I see it, life moves like a vortex. When it seems life has come around a full circle it is actually (and factually) displaced in time. So what seems like a point from the top view is actually a line in vertical plane.

If I were to construct an approximate model, time would be X-axis, life would be Y-axis and the displacement caused by the various external and internal factors would be Z-axis. You can be at the same place again but the time has moved and so have the external factors affecting the life. The image summarises it all.

Note: Special thanks to Alok Pradhan on making me think on my status message "Life never comes a full circle it moves in a vortex..."