Epicurus was also an early thinker to develop the notion of justice as a social contract. He defined justice as an agreement made by people not to harm each other. The point of living in a society with laws and punishments is to be protected from harm so that one is free to pursue happiness. Because of this, laws that do not contribute to promoting human happiness are not just. He gave his own unique version of the ethic of reciprocity, which differs from other formulations by emphasizing minimizing harm and maximizing happiness for oneself and others: