The setting at the Copley Symphony Hall is not unlike Leonard Cohen himself. With its stained-glass windows and walls of intricately sculpted marble, the building seems as though it should house sermons rather than symphonies. But at the center of the basilican architecture lies the stage itself, lit in smokey reds and swanky purples that would feel more at home in a brothel than a cathedral. The juxtaposition of the sacred and the profane has long been a tenet of Cohen’s distinguished career, which has been as defined by prayer songs like “If It Be Your Will†as it has by the lurid recounting of trysts with Janis Joplin.