There is no form of literature so old or so universal as graffiti. It's been around since the days of the cave painters and looks like it will be with us for the rest of time.

Graffiti can be about anything; such as, philosophical graffiti, political graffiti, protest graffiti, racist graffiti, graffiti about graffiti, and graffiti that manage to be about graffiti: "Down with graffiti!"

Brevity is the soul of wit and many of the best bits of graffiti are short, sharp slogans that pack a punch and promote a cause:

• Stop air pollution, quit breathing.
• Help stamp out philately.
• Help a nun kick the habit.
• Eggheads of the world unite! You have nothing to lose but your yokes.
• To save face, keep the lower half shut.
• Autopsy is a dying practice.
• Anarchists unite!.
• Fight poverty the American way, get a job.
• You're never alone with schizophrenia.