Andrew Duncan is best known as a pioneer of the humane treatment of the mentally ill. It was the experience of seeing the brilliant young poet, Robert Fergusson in great mental anguish and lying, like a prisoner, manacled on a bed of straw in a cell that made Duncan determined to establish a public lunatic asylum. The asylum was eventually built, in the Morningside area of Edinburgh, in 1807. Together with colleagues, Duncan brought about a change in the understanding of the nature of mental illness and the treatment of those who suffered from it.