John Updike discusses three books related to Max Ernst and his retrospective at the Met, in the New York Review of Books:
Not only is Max Ernst the subject of an extensive and eye-challenging retrospective at the Metropolitan Museum of Art, he is winning retrospective publicity as a romantic principal in a shameless, artistically high-powered ménage à trois in the early 1920s, lyrically and speculatively described by the documentary filmmaker Robert McNab in his Ghost Ships. The known facts are not numerous: Ernst, born in the town of Brühl, Germany, near the Rhine between Bonn and Cologne, into a large, middle-class, Catholic family, whose father was a teacher of deaf and mute children and an amateur painter, studied philosophy and abnormal psychology at the University of Bonn. At the age of twenty he decided to become a painter and joined August Macke’s Rhine Expressionist group. In 1919, having served four years in the Kaiser’s army and risen to the rank of lieutenant, he helped found, with Johannes Theodor Baargeld, the Cologne Dada movement. Increasingly well-known in art circles, and acquainted with such prominent German-speaking artists as Paul Klee, Hans Arp, George Grosz, John Heartfield, and Otto Dix, he experimented with collage.
More here. See also this on Ernst.