Rebecca Solnit takes the long view:
The revolution [in Egypt] was called by a young woman with nothing more than a Facebook account and passionate conviction. They were enough. Often, revolution has had such modest starts. On October 5, 1789, a girl took a drum to the central markets of Paris. The storming of the Bastille a few months before had started, but hardly completed, a revolution. That drummer girl helped gather a mostly female crowd of thousands who marched to Versailles and seized the royal family. It was the end of the Bourbon monarchy.
... That the flapping of a butterfly’s wings in Brazil can shape the weather in Texas is a summation of chaos theory that is now an oft-repeated cliché. But there are billions of butterflies on earth, all flapping their wings. Why does one gesture matter more than another? Why this Facebook post, this girl with a drum? ... The point is not that causation is unpredictable and erratic. The point is that butterflies and sparrows and young women in veils and an unknown 20-year-old rapping in Arabic and you yourself, if you wanted it, sometimes have tremendous power, enough to bring down a dictator, enough to change the world.
(Video: 26-year-old Asmaa Mahfouz of Egypt from January 18th)