Duncan was born in Gilcomston,
Aberdeen, the son of a shoemaker. He studied at
Marischal College in the
University of Aberdeen and obtained an
MA in 1814. Duncan embarked upon
theological study while still an
atheist, first through the
Anti-Burgher Secession Church and then the
Established Church. He completed his studies in 1821 and subsequently became a theist, but according to his later testimony was not yet converted when he was licensed to preach in 1825. Duncan was converted in 1826 through the ministry of
César Malan, and in 1830 commenced ministry at Persie in
Perthshire. The following year he moved to
Glasgow, and was finally ordained as the minister of
Milton parish church on 28 April 1836. On the occurrence of a vacancy in the chair of oriental languages in the
University of Glasgow, he offered himself as a candidate, stating in his application that he knew Hebrew, Syriac, Arabic, Persian, Sanscrit, Bengali, Hindostani, and Mahratti; while in Hebrew literature he professed everything, including grammarians, commentators, law books, controversial books, and books of ecclesiastical scholastics, and of
belles-lettres. His application failed, but his college gave him the degree of
LL.D. in 1840. , where Duncan was Professor of Hebrew and Oriental Languages for 27 years On 7 October 1840, as a consequence of an increased interest in the
Church of Scotland concerning the conversion of the
Jews, and of his own deep interest in Israel, Duncan was appointed the first
Missionary to the Jews from the Church of Scotland. He set out for
Pest (part of
Budapest) in
Hungary in 1841. Macleod writes that "since the days of the
Apostles there is hardly on record such a striking work of grace among the Jews as took place in the days of his labours in Buda-Pesth," and that
Adolph Saphir and
Alfred Edersheim were converted through Duncan's work there.
Duchess Maria Dorothea of Württemberg was most friendly, and helped the mission in many ways. Duncan stayed in Hungary for two years, until the
Disruption of 1843 led to an invitation to fill the chair of Hebrew and Oriental Languages at
New College, Edinburgh. Duncan occupied this position until his death in 1870. He is buried under a large obelisk in the north-east section of the
Grange Cemetery in Edinburgh. His tombstone refers to him as "an eminent scholar and metaphysician, a profound theologian, a man of tender piety and of a lowly loving spirit." ==Legacy==