Diogenes (c. 412–323 BCE) dominates the story of Cynicism like no other figure. He originally went to Athens, fleeing his home city, after he and his father, who was in charge of the mint at Sinope, got into trouble for falsifying the coinage. (The phrase "defacing the currency" later became proverbial in describing Diogenes' rejection of conventional values.) Later tradition claimed that Diogenes became the disciple of Antisthenes, but it is by no means certain that they ever met. Diogenes did however adopt Antisthenes' teachings and the ascetic way of life, pursuing a life of self-sufficiency (autarkeia), austerity (askēsis), and shamelessness (anaideia). There are many anecdotes about his extreme asceticism (sleeping in a tub), his shameless behaviour (eating raw meat), and his criticism of conventional society ("bad people obey their lusts as servants obey their masters"), and although it is impossible to tell which of these stories are true, they do illustrate the broad character of the man, including an ethical seriousness.
Diogenes was a controversial figure. He was the son of a mintmaster and was banished from Sinope for debasement of currency. After being exiled, he moved to Athens and criticized many cultural conventions of the city. He modeled himself on the example of Heracles, and believed that virtue was better revealed in action than in theory. He used his simple lifestyle and behavior to criticize the social values and institutions of what he saw as a corrupt, confused society. He had a reputation for sleeping and eating wherever he chose in a highly non-traditional fashion, and took to toughening himself against nature. He declared himself a cosmopolitan and a citizen of the world rather than claiming allegiance to just one place. There are many tales about his dogging Antisthenes' footsteps and becoming his "faithful hound".
Diogenes holding a lamp during daylight searching for an honest man.
Diogenes Searching for an Honest Man (1640–1647) by Giovanni Benedetto Castiglione held at the National Gallery of Art
Diogenes made a virtue of poverty. He begged for a living and often slept in a large ceramic jar, or pithos, in the marketplace. He became notorious for his philosophical stunts, such as carrying a lamp during the day, claiming to be looking for a man (often rendered in English as "looking for an honest man"). He criticized Plato, disputed his interpretation of Socrates, and sabotaged his lectures, sometimes distracting listeners by bringing food and eating during the discussions. Diogenes was also noted for having mocked Alexander the Great, both in public and to his face when he visited Corinth in 336 BC.
Diogenes was captured by pirates and sold into slavery, eventually settling in Corinth. There he passed his philosophy of Cynicism to Crates, who taught it to Zeno of Citium, who fashioned it into the school of Stoicism, one of the most enduring schools of Greek philosophy. No writings of Diogenes survive but there are some details of his life from anecdotes (chreia), especially from Diogenes Laërtius' book Lives and Opinions of Eminent Philosophers and some other sources.