Although posterity has generally known Bernardin de Saint-Pierre for his bestselling Paul et Virginie, his output was encyclopaedic. Using new sources, this monograph explores the many facets of a celebrity writer in the Ancien Regime, the Revolution and the early nineteenth century. Bernardin attracted a readership to whom, irrespective of age, gender or social situation, he became a guide to living. He was nominated by Louis XVI to manage the Jardin des plantes, by Revolutionary bodies to teach at the Ecole normale and to membership of the Institut. He deplored unquestioning adherence to Newtonian ideas, materialistic atheism and human misdeeds in what could be considered proto-ecological terms. He bemoaned analytical, reductionist approaches: his philosophy placed human beings at the centre of the universe and stressed the interconnectedness of cosmic harmony. Bernardin learned enormously from travel to Eastern Europe and the Indian Ocean. He attacked slavery, championed a national education system and advocated justice for authors. Fresh information and interpretation show that he belonged to neither the philosophe or anti-philosophe camp. A reformist, he envisioned a regenerated France as a nation of liberty offering asylum for refugees. This study demonstrates the range of thought and expression of an incontournable polymath in an age of transformation.