Pablo Picasso of postcards to raise funds for the Spanish Republican cause. In 1944, Picasso joined the French Communist Party, attended the World Congress of Intellectuals in Defense of Peace in Poland, and in 1950 received the Stalin Peace Prize from the Soviet government. Party criticism in 1953 of his portrait of Stalin as insufficiently realistic cooled Picasso's interest in Soviet politics, though he remained a loyal member of the Communist Party until his death. His dealer, D-H. Kahnweiler, a socialist, termed Picasso's communism "sentimental" rather than political, saying "He has never read a line of Karl Marx, nor of Engels of
Pablo Picasso by which time the artist had started to sign his work "Picasso"; before he had signed "Pablo Ruiz y Picasso". Picasso's Blue Period (1901–1904), characterized by sombre paintings rendered in shades of blue and blue-green, only occasionally warmed by other colours, began either in Spain in early 1901, or in Paris in the second half of the year. Many paintings of gaunt mothers with children date from the Blue Period, during which Picasso divided his time between Barcelona and Paris. In his austere use of colour and sometimes doleful subject matter – prostitutes and beggars are frequent subjects – Picasso