Livingstone believed that he had a spiritual calling for exploration to find routes for commercial trade which would displace slave trade routes, rather than for preaching. He was encouraged by the response in Britain to his discoveries and support for future expeditions, so he resigned from the London Missionary Society in 1857. According to his Victorian biographer W. Garden Blaikie, the reason was to prevent public concerns that his non-missionary activities such as his scientific work might show the LMS to be "departing from the proper objects of a missionary body". Livingstone had written to the directors of the society to express complaints about their policies and the clustering of too many missionaries near the Cape Colony, despite the sparse native population. Blaikie, not wishing to offend Livingstone's relatives, still living in 1880 when his book was published, concealed the real reason why Livingstone left the LMS and the manner of it. In a letter from the directors of the LMS, which Livingstone received at Quelimane, he was congratulated on his journey but was told that the directors were "restricted in their power of aiding plans connected only remotely with the spread of the Gospel".