The idea of the perfectibility of man emerges in the 18th century, with the relaxation of the theological barriers protecting the property for God alone. In Enlightenment writers such as Condorcet and Godwin, perfectibility becomes a tendency actually capable of being realized in human history. Before Kant, both Rousseau and the Scottish thinker Lord Monboddo (1714–99) envisaged perfectibility as the power of self-rule and moral progress. The 19th century represented the high-water mark of belief in perfectibility, under the influence first of Saint-Simon, then Kant, Hegel, Comte and Marx. With the arrival of the theory of evolution it was possible to see successive economic and cultural history as a progress of increasing fitness, from primitive and undeveloped states to a potential ideal associated with freedom and self-fulfilment. This optimism, frequently allied with unlimited confidence in the bettering of the human condition through the advance of science, has not generally survived the battering of the 20th century. See also absolute idealism, evolutionary ethics, postmodernism, progress.