Cologne and New York have both been decisive cities for American, European and Asian artists of the past 50 years. If in the 1960s and 70s their art scenes were characterized by a possibility of community and collective endeavor, in the 80s and 90s they experienced a surge of economic clout in a world focused increasingly on market "values." Through a network of references, connections and contrasts culled from critics, artists, gallery owners, collectors,...