Latvian-born scientist and Egypt specialist Georg Schweinfurth was funded by a scientific organisation in Berlin to travel to the Sudan between 1868 and 1871. The lurid account of his travels, 'The Heart of Africa', was a bestseller of European nineteenth-century travel writing on Africa, and one of the inspirations for the European abolitionist revival in the 1880s. In a chapter on his encounters with the slave trade in East Africa, Schweinfurth notes the strong demand and supply of slaves (he suggests more than 25,000 slaves were trafficked yearly from the Sudan) and argues that the trade would not disappear of its own accord. He stresses the contrast between West and East Africa in terms of slave trading, and argues that's Europe's work in Africa was only 'half complete', calling for direct intervention on the issue of slavery across the continent.