1806-1878. Scottish missionary to India. Born in Perthshire and educated at St. Andrews University, he became in 1830 the first church of Scotland missionary in India (he and his wife were twice shipwrecked en route to Calcutta). Realizing the value of a strong educational policy, he opened an English school in which the Bible was the central textbook, but which offered a variety of subjects to university standard. There was some opposition from both Hindus and fellow missionaries, but he had a powerful ally in the (British) governor general, and the school developed notably. Poor health compelled his return home in 1834, but he had recovered sufficiently to see India again in 1840.
When the Disruption* came in 1843, he like most missionaries left the establishment to form the Free Church of Scotland.* Consequently the Indian property had to be relinquished and the building of a new institution begun. In 1844 Duff helped to found the Calcutta Review, and was from 1845 its editor until he left for Scotland again in 1849. Earlier he had declined an invitation to succeed his old teacher Thomas Chalmers as principal and theology professor at New College, Edinburgh. In 1851 he was moderator of his church's general assembly, and in 1854 he impressed his concern for missions on American and Canadian listeners. Another address, delivered at an Evangelical Alliance gathering in 1855 was, said a friend, “like a trump of doom uttered over the worldliness of existing churches and a call to assembled Christendom to turn from luxury and pomp and to remember the perishing nations.” A further spell in India (1856- 64) was concerned with the advancement of higher education in the country, and with the foundation of the University of Calcutta. Ill health forced him to leave India, but he labored in the missionary cause until his death. From 1867 he occupied the first chair of evangelical theology at New College, Edinburgh.
See biographies by G. Smith (2 vols., 1879) and W. Paton (1923).