Circulus (theory)
Circulus was a socioeconomics doctrine devised by nineteenth-century French utopian socialist Pierre Leroux (1797–1871), who proposed that human excrement be collected by the state in the form of a tax and used as fertiliser, thereby increasing agricultural production sufficiently to prevent Malthusian catastrophe. == The theory == According to Leroux, human excrement has remarkable fertilising properties, which society fails to harness.