Although Leibniz is universally regarded as the greatest German philosopher before Kant, his work as a political and moral philosopher is almost entirely neglected in the English-speaking world, where he is seen chiefly as a metaphysician, mathematical logician, and co-discoverer of calculus. Yet Liebniz' doctoral degree was in law and jurisprudence, and he served throughout his life as a judge and a diplomat; he was a valued political-legal adviser to Czar Peter the Great, to the King of Prussia in Berlin, and to the Holy Roman Emperor in Vienna. Patrick Riley recovers this crucial part of Liebniz' thought and activity.