Of the many clues life provides to let us know holding on is of no benefit, the passing of a life is the strongest. As the monks who surround themselves with skulls of the deceased, this skull study reminds me of the truth in it all.
Impermanence; the nature of existence, and what a wonderful gift that is. It is all constantly breaking and falling apart, as if to say do not bother grasping at these objects and concepts all around you. After all it is fruitless and unnecessary. Freedom is in going with the river, not against. Swim with it; then you're at rest.
This is a topic I love! I will definitely cover this in more detail soon.