Leibniz’s Discourse on Metaphysics articulates a metaphysical architecture in which reality is intelligible because it is grounded in divine wisdom, not arbitrary power. Beginning with God as an absolutely perfect being, Leibniz rejects the view that goodness depends merely on God’s will; instead, perfection belongs to the rational nature of things, and God chooses the best because supreme freedom consists in acting according to reason. This principle develops into his account of creation as the selection of the most perfect order: the world is governed by laws that combine maximal richness of phenomena with maximal simplicity of principles. The decisive conceptual case is the individual substance. For Leibniz, a true substance contains within its complete notion all predicates that will ever belong to it; thus, Alexander’s conquering of Darius or Caesar’s crossing of the Rubicon are not accidental external additions, but intelligible within the complete concept of those individuals. Yet Leibniz avoids fatalism by distinguishing necessity from certainty: contingent truths are assured by God’s knowledge and by the chosen order of the world, but their opposites do not imply contradiction. This synthesis preserves both divine providence and created freedom. His further account of substances as mirrors of the universe establishes a profound pluralism: each being expresses the whole from its own viewpoint, while harmony is secured by God rather than by direct causal traffic between substances. The conclusion is exacting: individuality, freedom and order coexist because reality is not mechanical chaos, but rationally coordinated expression.