Why the Negativity is the Soul of Dialectics

why the dialectics of the soul and inherent nature is the negativity? This is the dialectic of their own critical thinking,and also show the logic of the key to understand why the dialectics of human existence.Dialectics,as a unique mode of thinking,was elaborated in order to overcome many difficulties and contradictions that the metaphysical faced.The negativity is the crucial feature for overcoming such difficulties and contradictions.The dialectics of the nature-negativity,in the final analysis,comes from the existence of human nature and the nature of the practice.