Cynicism (from Wikipedia)
Summary of Classical Cynicism: The purpose of life is to live in virtue and agreement with nature. As reasoning creatures, people could gain happiness by rigorous training and by living in a way which is natural for themselves, rejecting conventional desires for wealth, power, and fame. Instead, they were to lead a simple life free from possessions. The goal of life is eudaimonia (happiness, flourishing, prosperity) 'and mental clarity or lucidity —literally "freedom from smoke" which signified false belief, mindlessness, folly, and conceit.
Eudaimonia depends on self-sufficiency, equanimity, excellence, love of humanity, speaking openly and honestly, and indifference to the vicissitudes of life. One progresses towards flourishing and clarity through ascetic practices which help one become free from influences such as wealth, fame, and power. A Cynic practices shamelessness or impudence and challenges the laws, customs, and social conventions that people take for granted. Thus a Cynic has no property and rejects all conventional values of money, fame, power and reputation. A life lived according to nature requires only the bare necessities.
The Cynic way of life required continuous training, not just in exercising judgments and mental impressions, but a physical training as well since the health and vigor are necessary for the practice of what is good, depending equally on both mind and body. The most immediate influence for the Cynic school was Socrates. Although he was not an ascetic, he did profess a love of virtue and an indifference to wealth, together with a disdain for general opinion.
The rise of Imperial Rome, like the Greek loss of independence under Philip and Alexander three centuries earlier, may have led to a sense of powerlessness and frustration among many people, which allowed a philosophy which emphasized self-sufficiency and inner-happiness to flourish. The Cynic "must know that he is sent as a messenger from Zeus to people concerning good and bad things, to show them that they have wandered." Epictetus
Christians often employed the same rhetorical methods as the Cynics. Some Cynics were martyred for speaking out against the authorities. Christian writers would often praise Cynic poverty, although they scorned Cynic shamelessness.
As iron is eaten away by rust, so the envious are consumed by their own passion.
Pay attention to your enemies, for they are the first to discover your mistakes.
The most useful piece of learning for the uses of life is to unlearn what is untrue.
Observe your enemies, for they first find out your faults.
There are only two people who can tell you the truth about yourself - an enemy who has lost his temper and a friend who loves you dearly.
In a rich man's house there is no place to spit but his face.
No man is hurt but by himself.
Blushing is the color of virtue.
The mob is the mother of tyrants.
The foundation of every state is the education of its youth.
It is the privilege of the gods to want nothing, and of godlike men to want little.
What I like to drink most is wine that belongs to others.
Dogs and philosophers do the greatest good and get the fewest rewards.
[When asked what was the proper time for supper] If you are a rich man, whenever you please; and if you are a poor man, whenever you can.
When I look upon seamen, men of science and philosophers, man is the wisest of all beings; when I look upon priests and prophets nothing is as contemptible as man.