How does Ally Carter use imagery in Only the Good Spy Young?

Imagery:

"...when you're a spy, your life isn't defined by the lies you tell, but by the truths."

"Some people think the key to strength is knowing how to hit - how to shift your weight, time your blow, land the punch just right. But that's not it. As I stood peering through the crowd at my mother and the man who had taken me out of the safety of the mansion, I knew real strength is NOT hitting when what you want to do most is kill."