"I had been taught to look for monsters and devils and I found ordinary people"
Henri is beginning to see the folly of the war he so gladly joined for his idolized leader, or the folly of wars in general. He's been listening and following the propaganda of demonization of the opposite side of the war, not realizing until he came face to face with the people, that there are no devils and monster as their enemies, only ordinary people who built their lives, fought for their survival and lost everything they built.
"Will you kill people, Henri?"
I dropped down beside her. "Not people Louise, just the enemy"
"What is enemy"
"Someone who's not on your side."
In order to come with terms with the fact that going into the war means killing other people, young men like Henri have been "taught" (read manipulated) that the enemy is the monster, that enemy is not human. Henri will later discover, after he sees ordinary scared people instead of monsters, that the monster might be hiding elsewhere.
"I was happy but happy is an adult word. You don't have to ask a child about happy, you see it. They are or they are not. Adults talk about being happy because largely they are not. Talking about it is the same as trying to catch the wind."
Henri recalls his childhood happiness. In this lamentation of happiness we get to hear the author's tone. The author criticizes philosophers who talk about things like happiness and passion without taking part in them. Feelings are not something to be expressed with words, but to be felt. Talking too much about being happy becomes a paradox, where it goes more in favor of the opposite truth.
