President Obama led tributes to the “great soul” of Nelson Mandela Tuesday before a cheering crowd of tens of thousands of South Africans and a host of world leaders who gathered at a soccer stadium in Soweto. Using tribal phrases that delighted the crowd, Obama said the world would never again see a man like Mandela, the “last great liberator of the 20th century.” He drew a standing ovation after describing the transformative power of a single great leader. “It took a man like Madiba to free not just the prisoner, but the jailor as well,” he said. Obama shook hands with Cuban president Raúl Castro and kissed Brazilian president Dilma Rousseff as an unprecedented collection of leaders celebrated the life of Mandela. The dancing crowd, diminished by torrential rain, cheered most of the leaders but booed when George W. Bush and their current president Jacob Zuma appeared on giant screens.