Biblical Theology: "tracing" and "describing" revelation as an act of God

“Biblical Theology is that part of Exegetical Theology which deals with the revelation of God. It makes use of all the results that have been obtained by all the preceding studies in this department. Still, we must endeavor to determine more precisely in what sense this general definition is to be understood. For it might be said of Systematic Theology, nay of the whole of Theology, with equal truth, that it deals with supernatural revelation. The specific character of Biblical Theology lies in this, that it discusses both the form and contents of revelation from the point of view of the revealing activity of God Himself. In other words, it deals with revelation in the active sense, as an act of God, and tries to understand and trace and describe this act, so far as this is possible to man and does not elude our finite observation.

"In Biblical Theology both the form and contents of revelation are considered as parts and products of a divine work. In Systematic Theology these same contents of revelation appear, but not under the aspect of the stages of a divine work; rather as the material for a human work of classifying and systematizing according to logical principles. Biblical Theology applies no other method of grouping and arranging these contents than is given in the divine economy of revelation itself.” -- Geerhardus Vos, "The Idea of Biblical Theology as a Science and as a Theological Discipline"