Christian Wolff was a rationalist polymath and an influential leader of the early German Enlightenment. He was born in Breslau into an impoverished family of leather workers. In his academic career, he gained renown by teaching mathematics and became famous for systematizing and updating the German philosopher and mathematician Gottfried Wilhelm Leibniz. Wolff pioneered socio-economics, framed the idea of subsidiarity (the EU welfare model), and made lasting contributions to international law. He developed German into a philosophical language (e.g., coining Begriff), created a terminology still in use in the twenty-first century (e.g., "monism" and "dualism"), and dominated continental thought before Immanuel Kant in Germany, Switzerland, Poland, Southeast Europe, and Russia. In his philosophical work, he revived ontology as a systematic framework for the empirical sciences, and expanded the geometric method, a mathematical design for rational thought and conceptual reasoning. He advanced the...