 Whatever novelty the sermon series possesses is literary and theological. It partly consists in the rich skein of images Edwards uses to connect the events of redemption history. These include the model of a river and its tributaries, a tree and its branches, the construction of a building, the conduct of war, and “a wheel,” or “a machine composed of wheels” with its reminiscences both of Ezekiel's vision of the divine throne chariot and of clockwork (“Images of Divine Things,” no. 89; Edwards 1957–, vol. 11, 86). It also consists in Edwards' extension of typology, the practice of interpreting things, persons, or events (the “type”) as symbols or prefigurations of future realities (the “antitype”). Protestant divines had tended to restrict typology to figures, actions, and objects in the Old Testament which in their view shadowed forth Christ as their antitype. Edwards interprets the New Testament typologically as well, arguing that relevant passages prefigure events in the church's later history. Most radically, Edwards construes nature typologically. (Whether this constitutes a step towards Emerson and Thoreau, as some claim, is a moot point.) Finally, Edwards' emphasis on the objective side of God's act of redemption is comparatively rare in a Puritanism which tended to stress the redemption's application to individual souls. (The subjective side is extensively treated in a number of works of the 1730s and 1740s, however, the most important of which is Religious Affections.)