The idyllic model is defined (in opposition to pastoral) as an extended topos or model of the physical and social universe, descended from an older world-view, but also offering a stylized image of part of the social reality of the 18th century and early 19th century. It is an attempt to suggest a state of mankind as a humanistic response to the natural state, and proves relevant to socio-historical developments during a century and a half. The usefulness of the idyllic model reaches a peak in the later part of the 18th century; major difficulties arise when writers try to endow it with a universal validity and to establish working relationship between the idyll and energy. The Romantic rejection of the idyll results in a playful, ironic usage. By 1850 a didactic-ideological usage of the model emerges, that can still be traced in politics and philosophy.