World citizen has a variety of similar meanings, often referring to a person who disapproves of traditional geopolitical divisions derived from national citizenship. An early incarnation of this sentiment can be found in Diogenes of Sinope (c. 412 B.C.), the founding father of the Cynic movement in Ancient Greece. Of Diogenes it is said: "Asked where he came from, he answered: 'I am a citizen of the world (kosmopolitês)'". This was a ground-breaking concept, because the broadest basis of social identity in Greece at that time was either the individual city-state or the Greeks (Hellenes) as a group. The Tamil poet Kaniyan Poongundran wrote in Purananuru, "To us all towns are one, all men our kin." In later years, political philosopher Thomas Paine would declare, "The world is my country, all mankind are my brethren and to do good is my religion." Albert Einstein described himself as a world citizen and supported the idea throughout his life, famously saying "Nationalism is an infantile disease. It is the measles of mankind." World citizenship has been promoted by distinguished people from Walter Cronkite to Garry Davis, who has lived for 60 years as a citizen of no nation, only the world. Davis founded the World Service Authority in Washington, DC, which issues the World Passport (usually not considered a valid passport) to world citizens. In 1956 Hugh J. Schonfield founded the Commonwealth of World Citizens, later known by its Esperanto name "Mondcivitan Republic", which also issued a world passport; it declined after the 1980s.