Théodore Rousseau (1812–1867), arguably the most important French landscape artist of the mid-nineteenth century and a leader of the so-called Barbizon School, occupies a crucial moment of transition from the idealizing effects of academic painting to the radically modern vision of the Impressionists. He was an experimental artist who rejected the traditional historical, biblical, or literary subject matter in favor of “unruly nature,” a Romantic naturalism that confounded his contemporaries with its “bizarre” compositional and coloristic innovations. Lavishly illustrated and thoroughly documented, this volume includes five essays by experts in the field. Scott Allan and Édouard Kopp alternately examine Rousseau’s diverse techniques and working procedures as a painter and as a draftsman, as well as his art’s mixed economic and critical fortunes on the art market and at the Salon. Line Clausen Pedersen’s essay focuses on Mont Blanc Seen from La Faucille, Storm Effect, an early touchstone for the artist and a spectacular example of the Romantic sublime in the Ny Carlsberg Glyptotek’s collection. This catalogue accompanies an eponymous exhibition on view at the J. Paul Getty Museum from June 21 to September 11, 2016, and at the Ny Carlsberg Glyptotek from October 13, 2016, to January 8, 2017.