Leibniz’s commitment to the characteristica universalis and the scientia generalis rested on his conviction that logic is a mirror of the structure of reality. In his view, the principles that govern thought also governed reality. Reality, for Leibniz, meant first and foremost God, the eternal and infinite being encompassing all perfections. It is from Him and His eternal thoughts that the story of the world in which we find ourselves begins. Logic therefore led via metaphysics to philosophical theology. ‘Possible worlds and fundamental principles’ outlines some of Leibniz’s trademark philosophical views including on possible worlds, possible beings, identity, and the principles of non-contradiction and sufficient reason.