The Holy Trinity is the ontological principle of Christian systematic theology. Its external or objective cognitive principle is the divine Word, by which, through the prophets and apostles and with the illumination of the Spirit, God's incommunicable self-knowledge is accommodated to the saints. The internal or subjective cognitive principle is the redeemed intelligence of the saints. Systematic theology is thus ectypal knowledge (derived from God's disclosure of his archetypal self-knowledge), and a subaltern or subordinate science. Its matter is twofold: God, and all things in God. Accordingly, it is best arranged as a treatment of God in himself, followed by a treatment of the outer works of God, with a theology of the divine missions as the hinge between the two. This arrangement offers a synthetic and conceptual transposition of the primary language of Scripture.