The legacy of the eighteenth-century Enlightenment occupied an ambiguous place in nineteenth-century Scottish life. Its stunning record of achievement remained vivid and inspirational, particularly in the sciences; but the culture of free enquiry which the Moderates had fostered during the second half of the eighteenth century sat awkwardly in the nineteenth with the more ostentatiously Calvinist – and informally repressive – norms of the surrounding culture. It was a cold climate for freethinkers. David Hume himself had been a conspicuous outlier in the Scottish Enlightenment: an open debunker of Christian metaphysics and the very idea of the supernatural, he was markedly out of step with his Moderate protectors in the Kirk. Hume's works nevertheless comprised an important part of eighteenth-century Scotland's bequest to the nineteenth, encouraging a mode of freethinking which was obtrusively at odds with the suffocating ecclesiastical norms of the Victorian era. Atheism, agnosticism and materialism were unwelcome weeds in a society whose prim, Presbyterian bourgeoisie prided itself on overt displays of godliness and Calvinist orthodoxy. It is remarkable, indeed, how many nineteenth-century Scottish freethinkers, were first awakened to irreligion in their homeland, but – whether because of stifling social pressures or blocked opportunities – pursued careers elsewhere, most often in London's more liberal environment, or abroad in the Empire or United States.

The most celebrated case, certainly in the United States, is that of Frances Wright (1795–1852), better known as Fanny Wright, who was born in Dundee and spent a crucial period of her youth with a great-uncle, James Mylne (1757–1839), Professor of Moral Philosophy at Glasgow. It was here in Glasgow that she developed an interest in the pagan philosophy of Epicurus, the subject of her first book A Few Days in Athens (1822). Wright made two trips to the United States, eventually settling there. In the States she became a prominent critic of organised religion, slavery and the compartmentalisation of women, as well as an outspoken champion of birth control and sexual freedom. Yet Wright, atypical as she was in several respects, followed an all-too-typical pattern: the nineteenth-century Scottish freethinker who makes his or her name at a remove from the narrow constraints of Scotland itself.