here's to a grain of sand.

"What would happen if a plane dropped you in the middle of the Sahara Desert and you picked up a grain of sand and moved it on milimeter?"

I said "I'd probably die of dehydration."

He said "I just mean right then, when you moved that single grain of sand. What would that mean?"

I said, "I dunno, what?"

He said, "Think about it."

I thought about it. "I guess I would have moved a grain of sand."

"Which would mean?"

"Which would mean I moved a grain of sand?"

"Which would mean you changed the Sahara."

"So?"

"So? So the Sahara is a vast desert that's existed for millions of years and you changed it."

"That's true!" I said, sitting up. "I changed the Sahara!"

"Which means?"

...

"I changed the course of human history."

Extremely Loud and Incredibly Close
page 86, J.S. Foer