Loving God is our highest perfection for Leibniz. It secures our belief and trust in the Creator, which is integral to the sciences as well as faith. Those who love God have justification for reasoning, that is, they can rationally expect to arrive at truth. This is because love is a receptivity to the perfection all of things; loving God, then, is a disposition and tendency toward the most perfect being, the ens perfectissimum. Individuals who perceive the divine nature “do (...) not merely fear the power of the supreme and all-seeing monarch,” Leibniz writes, “but are assured of his beneficence, and lastly—and what brings everything together—burn with a love of God above all else.”1 In my dissertation, I argue that Leibniz’s qualification should be taken seriously: love of God “brings everything together.” The subject of my dissertation can be stated schematically. It consists of two pairs of claims, one pair philosophical, the other theological: A moral quality is required to secure our reason. From a most perfect unity, a moral quality follows. Love of God is our highest perfection. Love of God secures our reasoning. Both concern the security of reason, by which I mean the rational motivation for reasoning itself. They are reasons we ought to expect reasoning to lead to truth. Yet they do not form a tight demonstration: while an inference is clearly at work in the first pair, there are no inferences in the second. Also, there is a distinction between a moral quality and love for God. Unless they are identified, Leibniz’s philosophy and theology secure reasoning apart from one another. In 1686, Leibniz wrote his well-known “Discourse on Metaphysics.” A few months after, he composed a theological treatise, Examination of the Christian Religion. These texts, I argue, should be read side by side, and the first chapter compares how divine perfection secures our reasoning in both texts. Some Moderns’ notion of perfection—namely, Descartes’, Spinoza’s, and Malebranche’s—fail to secure our reasoning because their views entail arbitrariness in the world and the divine nature. But a proper sense of perfection, one that includes a moral quality, secures our reasoning by ensuring that everything is amenable to reason. Descartes also sought to secure our reasoning, and for the second and third chapters I compare his account with Leibniz’s own, then draw out the latter’s criticisms. For Descartes, the deity’s moral quality is characterized by an indifferent will, which is eminently and formally revealed throughout creation. Although recognizing the infinite source of all things directs our attention appropriate in the Cartesian system, Leibniz criticizes Descartes’ detached and indifferent God. When our disposition toward God is not characterized by love, we are less rational than otherwise. Leibniz finds intolerable moral implications in the Cartesian system, and I work out these implications in chapter three. Descartes’ criteria of true and false ideas does not settle dispute, but relies on “interior testimony.” Proper reasoning, then, does not tend toward unity among persons, and this is especially problematic in religious debate. Descartes’ method is Stoic, which also leads to trouble when it comes to church unity: one remains in the church by a sheer act of will, which can violate reason. Leibniz views such a detachment of faith and reasoning as dangerous, besides impoverishing the concept of reason altogether. Leibniz’s notions of God and perfection secure our reason by engendering love for God. “Discourse” and Examen begin with a moral disposition and tendency. In the last chapter, I argue that this is the case by considering two criteria Leibniz adopts—his test for perfection and the kinds of knowledge—as well as the foundation of his logic at the time. Leibniz can tolerate provisional beginnings, hypothetical truths, and original sin because of his robust conception of love. He distinguishes two ways we love God: spes, or hope, is a disposition or tendency to natural perfection, and caritas, or esteem, affection, or love, regards divine perfection. These states orient us according to the divine plan. Miracles are within the world as an effect of the deity’s moral quality: they are a means God personally relates to rational beings. Miracles reveal the moral effects of our perception of phenomena generally, included the regularity observed and classified by science. So, to conclude, I compare Leibniz’s discussion of revelation in Examen with his discussion of miracles in “Discourse” to draw out the significance of miracles for him. Besides much debate on the implications of miracles for his conception of substance, I argue that there is a moral motivation for retaining miracles, even those of the second rank. (shrink)