"What is the first rule of Allomancy?" Vin asked. "The first thing I taught you?"
"Consequence," Elend said. "Every action has consequences. When you Push on something heavy, it will push you back. If you Push on something light, it will fly away."
It was the first lesson that Kelsier had taught Vin, as well as—she assumed—the first lesson his master had taught him.
"It's a good rule," Elend said, turning back to his contemplation of the horizon. "It works for all things in life. If you throw something into the air, it will come back down. If you bring an army into a man's kingdom, he will react . . ."
Consequence, she thought, frowning. Like things falling back when thrown into the sky. That's what Ruin's actions feel like to me. Consequences. Perhaps it was a remnant of touching the power, or perhaps just some rationalization her unconscious mind was giving her. Yet, she felt a logic to Ruin. She didn't understand that logic, but she could recognize it.