This book compares the two golden ages of private international law (PIL): the first is the era of Story and Savigny in the nineteenth century, while the second comprises the last fifty years. The period between 1970 and 2020 has been one of rapid changes and dense legislative responses, exemplified by the adoption of over one hundred national PIL codifications and almost as many international or regional conventions and regulations. These instruments provide a rich source for this book's incisive and instructive comparisons and a fertile ground for a reliable assessment of the progress of PIL as a discipline. This book skillfully uncovers and meticulously documents the gradual--and largely unnoticed--transition of PIL from the idealism of the nineteenth century to the pragmatic eclecticism and pluralism of the twenty-first century.