This passage can be found as the first paragraph of the Second Part of Rousseau’s Discourse on the Origin of Inequality. It is one that encapsulates most of his general ideas that can be found in the Discourse in a single paragraph. Rousseau’s philosophy is that by nature, humans are essentially peaceful, content and equal. “It is the socialization process that has produced inequality, competition and the egoistic mentality.” (Internet Encyclopedia of Philosophy)
Rousseau opens with the observation that the human race would have been spared great misery and cries if the first person who claimed to have appropriated a plot of land as his private property had been exposed as an impostor and not allowed to maintain his appropriation. By the time this event occurred it was probably