In the spring of 1672, the German philosopher and mathematician Gottfried Wilhelm Leibniz arrived in Paris on a furtive diplomatic?mission. That project was abandoned quickly, but Leibniz remained in Paris with a singular goal: to get the most out of the city's intellectual and cultural riches. He benefited, above all, from his friendships with France's two greatest philosopher-theologians of the period, Antoine Arnauld and Nicolas de Malebranche...