Two lectures given by the medical missionary and explorer David Livingstone after his return to England from his travels in Africa (1841-1856) form the core of this book, which was originally published in 1858, the year when Livingstone set off on the British Zambezi expedition. The book also contains a biography, a letter from Adam Sedgwick (then Professor of Geology at Cambridge), and a thorough appendix covering the scientific results of the journey, describing the geography, mineralogy, diseases, and the language and cultural aspects of the peoples Livingstone encountered. Finally, Livingstone reports on the needs and prospects for further missionary work in Africa. Although Livingstone himself felt his calling was now to pursue purely scientific exploration, he hoped that the lectures and their subsequent publication would encourage other missionaries to continue his work of evangelisation.