Surrealist automatism is a method of art-making in which the artist suppresses conscious control over the making process, allowing the unconscious mind to have great sway. Early 20th-century Dadaists, such as Hans Arp, made some use of this method through chance operations. Surrealist artists, most notably André Masson, adapted to art the automatic writing method of André Breton and Philippe Soupault who composed with it Les Champs Magnétiques (The Magnetic Fields) in 1919. The Automatic Message (1933) was one of Breton's significant theoretical works about automatism. Automatism has taken on many forms: the automatic writing and drawing initially (and still to this day) explored by the surrealists can be compared to similar or parallel phenomena, such as the non-idiomatic improvisation. "Psychic automatism in its pure state" was how André Breton defined Surrealism, and while the definition has proved capable of significant expansion, automatism remains of prime importance in the movement. Automatic drawing was first written about by the English artist Austin Osman Spare who wrote a chapter, Automatic Drawing as a Means to Art, in his book, The Book of Pleasure (1913). Other artists who also practised automatic drawing were Hilma af Klint, André Masson, Joan Miró, Salvador Dalí, Jean Arp, André Breton and Freddy Flores Knistoff. The technique of automatic drawing was transferred to painting (as seen in Miró's paintings which often started out as automatic drawings), and has been adapted to other media; there have even been automatic "drawings" in computer graphics. Pablo Picasso was also thought to have expressed a type of automatic drawing in his later work, and particularly in his etchings and lithographic suites of the 1960s. Automatic drawing (distinguished from drawn expression of mediums) was developed by the surrealists, as a means of expressing the subconscious. In automatic drawing, the hand is allowed to move "randomly" across the paper. In applying chance and accident to mark-making, drawing is to a large extent freed of rational control.