From the perspective of hermeneutics-dimension, to understand Hegel's dialectics, we should begin with the embryo of the prehistory of his thinking and then its development and even turning in its generative history. This article starts from the origin of Hegel's dialectical philosophizing, i.e., the beginning of the Frankfurt period, to discover the relationship between the infinite life-Being and finite reflection in the panentheism and its dynamics as dialectics of love. Then it will treat the famous Jena period: First, in the early stage of Jena, his philosophizing showed the absolute metaphysics as the relationship between the monistic substance and the human subject and its negative dialectics. Hereafter there was a crutial turn in the middle Jena period, that is, a paradigm shift from the substance metaphysics to the systemic philosophizing of spirit. This article mainly explores and presents the key to this shift, i.e., its history from the Frankfurt period to the early middle Jena period as prehistory of the transforming to the dialectics of spirit.