Two developments shook the world of visual art in the mid-19th century. The first was the invention of the photographic camera, which arguably spurred the development of Realism in art. The second was a discovery in the world of mathematics of non-Euclidean geometry, which overthrew the 2000-year-old seeming absolutes of Euclidean geometry and threw into question conventional Renaissance perspective by suggesting the possible existence of multiple dimensional worlds and perspectives in which things might look very different.[7]