input: [CIRCULAR to 1720] Plato Ibn Khaldun Medieval scholastics [PROGRESSIVE c. 1720-1790] Montesquieu Turgot Ferguson Adam Smith [PESSIMISM c. 1790-1820] Malthus Tocqueville (Maine) Romantic movement [EVOLUTIONARY c. 1840-1890] Darwin Marx and Engels Spencer Morgan Tylor Avebury [DIFFUSIONIST c. 1890-1920] Haddon Perry Rivers (late) Elliott Smith (Frazer) [0] 
output: PEOPLE
options: P E O P L E
options: T I M E
options: P O W E R
options: M E T A P H O R
options: Q U E S T I O N
options: M O D E L
options: V A L U E