What is generally referred to as the first Cubist picture ?
According to the English art historian , collector and author of " The Cubist Epoch " , Douglas Cooper , both of those artists were particularly influential to the formation of Cubism and especially important to the paintings of Picasso during 1906 and 1907 . Cooper goes on to say however " Les Demoiselles " is often erroneously referred to as the first cubist painting .