From the obituary written by Roberta Smith:
Sigmar Polke, an artist of infinite, often ravishing pictorial jest, whose sarcastic and vibrant layering of found images and maverick, chaos-provoking painting processes left an indelible mark on the last four decades of contemporary painting, died yesterday in Cologne, Germany. He was 69; the cause was complications of cancer, according to Gordon Veneklasen, a partner at the Michael Werner Gallery New York, the artist�s chief American representative….
Polke’s main achievement was to be an early and astute adopter of American Pop Art, belying its crisp, consumerist optimism with tawdry materials that added social bite, and with random splashes of paint that implied disorder and the unconscious. His paintings were essentially Conceptual in their skepticism about the very act of painting. His images rampaged through history, ranging from demure 18th-century prints of an aristocratic astronomer that slyly signaled his interest in optics to images of the watchtowers and barbed-wire fences of Hitler�s concentration camps, stenciled onto banal printed fabric. The images questioned accepted taste, challenging the viewer to think through how they had been made; their random juxtapositions often seemed to mimic thought itself. In all these ways he opened the door to a freewheeling combination of representation and abstraction that is still playing out….