Cynicism is a school of thought in ancient Greek philosophy, originating in the Classical period and extending into the Hellenistic and Roman Imperial periods. According to Cynicism, people are reasoning animals, and the purpose of life and the way to gain happiness is to achieve virtue, in agreement with nature, following one's natural sense of reason by living simply and shamelessly free from social constraints. The Cynics rejected all conventional desires for wealth, power, pleasure, glory, social recognition, conformity, and worldly possessions and even flouted such conventions openly and derisively in public.