more blunt; refusing to shake hands with Picasso, he told him: "I don't approve of your joining the Communist Party nor with the stand you have taken concerning the purges of the intellectuals after the Liberation." As a communist, Picasso opposed the intervention of the United Nations and the United States in the Korean War, and depicted it in Massacre in Korea. The art critic Kirsten Hoving Keen wrote that it was "inspired by reports of American atrocities" and considered it one of Picasso's communist works. On 9 January 1949, Picasso created Dove, a black and white lithograph. It was used to illustrate a poster at the 1949 World Peace Council and became an iconographic image of the period, known as "The dove of peace". Picasso's image was used around the world as a symbol of the Peace Congresses and communism. In 1962, he received the Lenin Peace Prize. Biographer and art critic John Berger felt his talents as an artist were "wasted" by the communists. According to Jean Cocteau's diaries, Picasso once said to him in reference to the communists: "I have joined a family, and like all families, it's full of shit." Style and technique Picasso was exceptionally prolific throughout his long lifetime. At his death there were more than 45,000 unsold works in his estate, comprising 1,885 paintings, 1,228 sculptures, 3,222 ceramics, 7,089 drawings, 150 sketchbooks, many thousands of prints, and numerous tapestries and rugs. The most complete – but not exhaustive – catalogue of his works, the catalogue raisonné compiled by Christian Zervos, lists more than 16,000 paintings and drawings. Picasso's output was several times more prolific than most artists of his era; by at least one account, American artist Bob Ross is the only one to rival Picasso's volume, and Ross's artwork was designed specifically to be easily mass-produced quickly. The medium in which Picasso made his most important contribution was painting. In his paintings, Picasso used colour as an expressive element, but relied on drawing rather than subtleties of colour to create form and space. He sometimes added sand to his paint to vary its texture. A nanoprobe of Picasso's The Red Armchair (1931), in the collection of the Art Institute of Chicago, by physicists at Argonne National Laboratory in 2012 confirmed art historians' belief that Picasso used common house paint in many of his paintings. Much of his painting was done at night