One day... one lunar cycle... one year... one incarnation...
All of these can be laid upon the Wheel of Life. It connects us to our past, to our future, it shows us who and where we are.
The energy of the new day surges, then lapses into sleep; the new moon waxes, then wanes into another cycle; the power of the sun on the land grows through the year and then diminishes; and so our time on earth from our birth to our death is a cycle of energy that waxes and wanes before returning to the earth.
Cycles are evident in all things. We now know that our planet recycles herself. As new land erupts from the depths so the old is taken back via the mechanism of tectonic plates. All galaxies have a black hole in the centre recyling the material particles.
In the physical world, no particular state lasts forever; everything that comes, comes to pass. As you look back on your own life you will see evidence of this.