All Buddhist practice is for the purpose of working to become free of the basic problem of suffering, and it's all based on the possibility of an inner transformation, the transformation of our perception, our view.
If we can let go of the state of mind which is always in turmoil, always either running away from something or running after something, we can find fearlessness, liberation and peace.
The teaching on the four noble truths is the basis of understanding of all Buddhist teachings and practices; it's the basis of everything.