This, Witsius's magnum opus is a reflection of some of the most fruitful and mature thinking on federal theology during the seventeenth century. It still holds and preeminent place today. Reformed theology has always understood the biblical doctrine of the covenant to be the theological framework that best unifies Scripture to make a consistent hermeneutic. Witsius presents the reader with a fully biblical and experiential doctrine of the divine covenants, opening up their nature, stipulations, curses, and blessings. Anyone interested in reformed theology should read these volumes, for they represent Reformed theology at its best.