The term 'In Surrealism Pioneer' refers to the German artist, Max Ernst. He was a leading figure in the Dada and Surrealist movements of the early 20th century. Ernst was known for his unconventional painting techniques, such as frottage and grattage, which he used to create dreamlike images. He also experimented with sculpture, collage, and other media. Ernst's work was highly influential in the development of Surrealism, and he is considered one of the most important artists of the 20th century.