Why was the democratic transition in South Africa viable?

On October 11, 1996, the National Parliament of the new Republic of South Africa unanimously approved a new democratic constitution. The constitution emerged from over six years of negotiations between South Africa’s once ruling white elite represented by the National Party (NP) led by F. W. de Klerk and the long oppressed Black and Asian majorities represented by the African National Congress (ANC) led by Nelson Mandela.