Whilst seated beneath the Bodhi tree the Buddha experienced the four noble truths:
Dukkha: All existence is unsatisfactory and filled with suffering.
Trsna: The root of suffering can be defined as a craving or clinging to the wrong things; searching to find stability in a shifting world is the wrong way.
Nirvana: It is possible to find an end to suffering.
The Noble Eightfold Path is the way to finding the solution to suffering and bring it to an end.