6377182 Moonlight on the Road, Illustration for Linear Perspective, table IV 1838-40 (etching) by Eckersberg, Christoffer-Wilhelm (1783-1853); Statens Museum for Kunst, Copenhagen, Denmark; (add.info.: Copenhague, Statens Museum for Kunst In 1841, Eckersberg and the mathematician G. F. Ursin published a treatise on linear perspective applied to painting. Through texts and illustrations such as this one, he breaks down perspective and optics to explain the principles of composition and how light and shadow come into play.); Photo 穢 Sylvain Collet.