 In the eighteenth century its influence may be found in the works of the theological utilitarians, Abraham Tucker ("The Light of Nature Pursued", 7 vols., 1768–1778) and William Paley ("Principles of Moral and Political Philosophy", 1785).David Hartley said that Gay's assertion of the importance of psychological association in human nature was the origin of his "Observations on Man" (1749).In 1730 Gay resigned his fellowship and became Vicar of Wilshampstead, later adding the living of Haynes.