"A butterfly can flap its wings in America and cause a hurricane in China."
Vash poked his brother. "You're just quoting Rem. You have no idea what that means."
Knives' smirk faded. "Well neither do you." He paused. "Rem, what's a hurricane?"
"It's...sort of a mixture of extreme winds and water. Two of the four main elements. Remember?"
Vash spoke up after a moment's silent consideration. "What's wind again?"
"It's...well, it's...gravitational forces can...and the air..." She stopped, frowned. How could she explain wind to two people who had never before seen a sky?