Diogenes (400-325 B.C.) was a Greek philosopher who became the most famous of the Cynics. In adherence to his philosophy, Diogenes lived in severe poverty. According to legend, he lived in a tub. His nickname was Greek for "the dog," from which the name "Cynic" derives. His teacher was Antisthenes.
Upon the arrival of Alexander the Great in Athens, the home of Diogenes, the great king is said to have approached Diogenes and said, "Great Diogones the philosopher, ask of me anything you wish, and it is yours," to which Diogenes replied, "I ask that you step away - you are blocking the sun." This demonstrated Diogenes' contempt for worldly goods, worldly mores, and social standing.
Diogenes also believed in rejecting social conventions. For example, he supposedly carried a lantern by day, not by night, because he said "he used it to look for an honest man."
Because Diogenes believed that virtue was better revealed in action than in theory, he made his life a protest against what he thought of as a corrupt society... In later art, Diogenes is often depicted in a torn cloak, with a dog, carrying a lantern. 
Note: Another Greek, Diogenes Laertius (ca. 200-250 AD), wrote perhaps around 240 AD about the life of famous Greek philosophers (Lives and Maxims of Those who Have Distinguished themselves in Philosophy and the Doctrines of Each Sect, in ten books).