The Buddha taught that everything is impermanent; that nothing is an absolute entity that remains the same. When we keep that insight in mind, we can see more deeply into the nature of reality, and we won’t be trapped in the notion that we’re only this body or this life span.

Understanding impermanence isn’t a matter of words or concepts. It’s a matter of practice… The object we’re observing might be a flower, a leaf, or a living being. Looking at this object deeply, we can see the change taking place in every instant.
There’s no independent individual phenomenon because everything is changing all the time. A flower is always receiving non-flower elements such as water, air, and sunshine, and it’s always giving something back to the environment. A flower is always being born and always dying, always connected to the environment around it. The components of the universe depend on one another for their existence.
The example of a wave and water is often given to help us understand the non-self nature of all that exists. A wave can be high or low, can arise or disappear, but the existence of the wave- water – is neither high nor low, neither arising nor disappearing. All signs- high, low, arising, disappearing – cannot touch the essence of water. We cry and laugh according to the sign, because we haven’t yet seen the essence- that is the very nature of everything that is. And this is the reality of ourselves. If we only see the wave with its manifestations of being born and dying, we will suffer. But if we see the water, which is the basis of the wave, and we see that the waves are returning to water, we have nothing to fear.
A drop of rain falling on the ground disappears in no time at all. But it is still there somehow, even if it is absorbed into the soil, it’s still there in another form. If it evaporates, it’s still there in the air. It’s become vapor; you don’t see the drop of rain, but that doesn’t mean it’s no longer there. A cloud can never die. A cloud can become rain or snow or ice, but a cloud cannot become nothing. to die means from something we become nothing, from being we pass into nothing. That is our idea of death. But meditation helps us to touch our true nature of no-birth and no-death. before the cloud manifests as a cloud, the cloud has been water vapor, has been the ocean. So it has not come from nonbeing into being. Our notion of birth is just a notion. Our notion of death is just a notion
Excerpt from The World We Have: Chapter V (pg 59) by Zen Master Thich Nhat Hanh