COUNT CARL GUSTAF TESSIN (1695-1770) the Swedish diplomat and politician, was one of Sweden's greatest art collectors. During his time as ambassador in Paris, from 1739 to 1742, he purchased and commissioned a great amount of art. Today, after more than 260 years, Tessin's art collection continues to fascinate, as he personified ideals of knowledge, taste and refinement. This reflected the new role of the arts during the Enlightenment and paved the way for the museum institution. Many of Tessin's collected objects make up the foundation of the Nationalmuseum in Stockholm and constitute the only private collection of French art from the Ancient Regime to survive intact, including original frames and correspondence with leading artists, dealers and connoisseurs in 18th century Europe. This volume contains a number of essays by international experts and scholars and aims to shed light on the close relationship between the art collection practice and Enlightenment ideas regarding science, knowledge and society which continues to be essential to all museums worldwide. They were first presented at a research colloquium at INHA in Paris in January 2017 arranged by Axel and MargaretAx:sonJohnson Foundation together with the Louvre Museum.