Group of Trees, 1858. The purest expression of the pastoral in French landscape in the mid 19th century may be found in the work of Corot. In the clich?-verre prints that he created between 1854 and 1874, Corot took advantage of the spontaneity of this simple process. Drawing directly on a glass plate coated with collodion, and then printing it like a photographic negative, Corot developed a loose, free style of draftsmanship that was unparalleled in his painting. Prints such as these were made purely for his own pleasure and were not intended for sale. Graceful, fluid lines flow from tree to tree and from tree to land, blending into each other without interruption, suggesting a harmony uniting all of nature.