The astonishing Jörg Immendorff: The Task of the Painter at the Museo Nacional Centro de Arte Reina Sofía, the first full retrospective since the artist’s death in 2007, includes about 100 works, mostly paintings, from all periods of his career. Born in 1945, he was a pupil and close friend of Joseph Beuys, but apparently revolted against that early influence, which he recorded in the painting “Beuys as a Non-Swimmer” (1968).Expelled from the Düsseldorf art school, the Kunstakademie, for his political activities as a member of the Communist Party of Germany — a splinter group opposed to the German Communist Party, the Soviet regime, and, of course, the United States — in the 1970s Immendorff made political propaganda paintings.Like comic strip images, these early works often include detailed written commentary. In “Where Do you Stand with Your Art, Colleague?” (1973), the artist, shown working in his studio, is called upon to join the revolution in progress right outside his door. Rebelling against the vestiges of Nazism and colonialism in the West German government in a related painting, the text-heavy “For Whom” (1973), Immendorff lists “Drei Beispiele” — three examples — of how an artist can “serve the people with his work.” And “Frankfurt/Main” (1973) depicts a demonstration against the Vietnam War.In the late 1970s, in response in part to the changing German political situation, Immendorff did the Café Deutschland paintings, images of stage sets, theaters in the round, in which the contemporary history of his country is being enacted. In the first picture, “Café Deutschland” (1978) Immendorff, seated at the left front, stretches his hand through the broken wall, as if to welcome us, while in “Café Deutschland XI – Parliament 2” (1981), he depicts an indescribably chaotic scene including an orgy, chess players, and musicians.It’s as if the world of the Bertolt Brecht / Kurt Weill Threepenny Opera (1928) were updated, enlarged, and depicted in color. Indeed in 1976 Immendorff did a six-part Brecht Cycle: Questions from a Worker Who Reads, with word/image combinations, like in his earlier aigitprop pictures. His elliptical response to the 1989 reunification of Germany, “3rd October 90” (1990), in which he shows himself sitting at a table with Max Ernst, while André Breton brings them a crate of cucumbers should give scholars of Surrealism a field day.Immendorff’s later work is not as easy to understand. In “Painter as Canvas” (1990-91), a self-portrait of the artist at work, what is the significance of the face he is painting, and who are the many figures in the background? And in “Final Self-Portrait I-The Picture Calls” (1998), in which the artist is immersed in a black field, what is the meaning of the fragmented images that appear around him — one a holiday scene but the others harder to make out?In 1998 Immendorff contracted amyotrophic lateral sclerosis, which drastically restricted his mobility, forcing him to give up working with his right hand. “I still take up the brush directly,” he wrote: “but I am more destructive, I work, as odd as that sounds, destructively in pictorial terms, which I always wanted to do.”Look if you will at “The Image Has to Assume the Function of the Potato” (1988). In the foreground you see a group of cooks and bottle washers, and in the background, a golden restaurant. What is happening here? I haven’t the slightest idea, but this visual cacophony is enthralling.Or consider “In Café Flore (with Max, Otto, Ernst)” (1987) in which Immendorff acts as the waiter, serving Otto Dix, Ernst-Ludwig Kirchner, and Max Beckmann, keeping one drink for himself. The catalogue caption reads, in part: “That a boar grunts under a see-through sheet […] is a minor breach of etiquette, yet we must bear in mind that he tends to be well behaved […] .” That hardly helps. The picture-plus-interpretation is clinically crazy, but, at least for me, it is totally captivating. Perhaps that is the point: Only such an image can truthfully represent our world.The exhibition catalogue is 700 pages, and anyone who wants to understand late 20th-century painting is going to have to work through it with close care, for it’s obvious that during his lifetime Immendorff was one of the most important artists anywhere. In the 1980s, when a great deal of German painting was shown in New York, Anselm Kiefer and Gerhard Richter were easier for Americans to understand. Because Immendorff’’s pictorial allusions, very often, refer to details of contemporary German history, his work was (and still is) more elusive. He came of age as an artist at a time when, in the United States, the viability of painting itself was much questioned. How different was the situation in Germany!Imagine Gustave Courbet’s materialism joined to Max Beckmann’s aggressive color, with a dash of Caspar David Friedrich’s visionary panoramas thrown in, and you have something like Immendorff’s sensibility. At least that’s how it looks to me, speaking as an outsider. He could play naïve, but he’s not ironical. He doesn’t do subtlety, and he has a very German sense of humor. Immendorff is an urban artist — nature doesn’t concern him. He’s not interested in the status of abstraction, which concerned his American peers. His political art is blunt but truthful. A nighttime painter, what most fascinates him is the material stuff of the world and, as I have said, the conception that the world is a stage set.Is it possible to be seized by an artist’s greatness without understanding the work? That was my experience in Madrid. But perhaps I needed this large retrospective to inspire me. When last summer I saw the smaller Immendorff exhibition, Ichich, Ichihr, Ichwir/We All Have to Die in Venice, I was fascinated but puzzled. Now, however, my sense of his art is clearer.Immendorff is a great artist because he is endlessly inventive, because he is a convincing political painter, because he extends pictorial tradition in boldly original ways. Compared to his works, Roy Lichtenstein’s and Andy Warhol’s paintings are mostly very static, Frank Stella’s formulaic, and Peter Saul’s oddly gawky. He has said: “I am a narrator with a superabundant urge to concoct stories, someone who perhaps comes right out of a fairy tale.”Superabundant is right. Even if you don’t understand his subjects, or dislike his paintings, you cannot but agree that this self-evaluation is spot-on.