"What about it, Meta?" he snapped. "No doubts? Do you think that destruction is the only way to end this war?"
"I don't know," she said. "I can't be sure. For the first time in my life I find myself with more than one answer to the same question."
"Congratulations," he said. "It's a sign of growing up."

p. 113 - Deathworld (1960)