The essential idea of Leibniz’s Theodicy was little understood in his time but has become one of the organizing themes of modern mathematics. There are many phenomena that are possible locally but for purely mathematical reasons impossible globally. For example, it is possible to build a spiral staircase that is rising at any given point, but it is impossible to build one that is rising at all points and comes back to where it started. The necessity is mathematically provable, so (...) not subject to exception by divine power. Leibniz’s Theodicy argues that God could improve the universe locally in many ways, but not globally. This paper defends Leibniz, giving positive reasons for believing that there are so many necessary interconnections between goods and evils that God is faced with a choice like the classic Trolley case, where all of the scenarios that could be chosen upfront contain evils, but some more than others. Local changes for the better seem easy to imagine, but a proper understanding of global constraints undermines the initial impression that they can be done without global cost. The paper concludes by explaining how the context of the Leibnizian argument makes it reasonable to pursue the issue of whether there are no worlds better than this one. (shrink)