The Buddha taught three things  about human life. These are what he discovered in his spiritual journey. They are all connected. They are: suffering, impermanence, and no-self.
Human existence is full of pain and frustration. Careful examination of our situation in life makes this very clear. If we don’t immediately see pervasive suffering in our own lives, we can certainly see it at any moment by turning on the news.
Why do we suffer?
Because all things are impermanent. Most of us live our lives as though things will last forever. A lot of our trouble arises because of our expectation that things will last. No matter how good or bad things are, they’re always going to change. This includes things like our thoughts and emotions, as well as big things like mountains and forests. Accepting this reduces our suffering.
No-self is the one people struggle with sometimes. Meditation is what helps us to detach from our idea that we are fixed beings, separate from the world around us. It’s our sense of self that makes us cling to things and also lash out. Holding onto this small self, what I call the “I-Me-Mine” that brings us a lot of suffering.
Looking at life, the Buddha saw that ignorance of the real nature of things causes people to be trapped in cycles of suffering.