HALIFAX – It is a gleaming monument intended to shed light on one of the darkest chapters of Canadian history.The Wheel of Conscience, designed by renowned architect Daniel Libeskind, will be unveiled Thursday at Pier 21, Canada’s immigration museum in Halifax. The cylindrical steel sculpture memorializes Canada’s shameful decision in 1939 to turn away a steamship carrying more than 900 Jewish refugees fleeing Nazi Germany. The luxury liner, MS St. Louis, was forced to sail back to Europe, where about 250 of its passengers later died in the Holocaust. Libeskind has said the central elements of the imposing mechanical sculpture are four spinning gears, symbolic of the guts of a ship’s engine and “a cynical bureaucracy.”The words hatred, racism, xenophobia and anti-Semitism appear on the face of each gear, with an image of the St. Louis in the background. The shiny cylinder is surrounded by the map of the world showing the ship’s route.”The gears … provide the mechanism to move the wheel in the vicious circle that brought tragedy to so many lives and shame to Canada,” Libeskind says on his website.The son of Holocaust survivors in Poland, Libeskind is best known as the master planner behind the ambitious 2003 proposal to create a row of cascading office towers to replace the World Trade Centre complex destroyed by terrorists on Sept. 11, 2001.