 Caldwell won a scholarship to Balliol College, Oxford only to find it rescinded when the authorities discovered that he had been born in Ireland.He responded by joining the London Missionary Society, who sent him to the University of Glasgow for training.There Caldwell came under the influence of Daniel Keyte Sandford, a professor of Greek and promoter of Anglicanism whose innovative research encouraged Caldwell's liking for comparative philology and also theology.