Before his leg breaks in chapter 4, Phineas talks as if he knows everything there is to know about the war. He does this because he is excited to enlist. After recovering from a broken leg at home for awhile, Phineas returns to Devon speaking as if the war doesn't exist. For example, Phineas tells Mr. Ludsbury in chapter 8 that he is training Gene for the 1944 Olympics. Finny's goal is crazy because, at this point in the story, World War II rages on without an end in sight. Mr. Ludsbury tells the boys that all exercises are aimed at training boys for war. Finny replies with a solid "No" because he supposedly believes there is no war and that the 1944 Olympics are a reality. Gene is dumbfounded, but permits himself to be drawn into Finny's charade by saying the following:
This was my first but not my last lapse into Finny's vision of peace. For hours, and sometimes for days, I fell without realizing it into the private explanation of the world. Not that I ever believed that the whole production of World War II was a trick of the eye manipulated by a bunch of calculating fat old men. . . What deceived me was my own happiness; for peace is indivisible, and the surrounding world confusion found no reflection inside me. So I ceased to have any real sense of it (123).
This passage points out that Gene feels peace and happiness by accepting Finny's world without a war. By accepting Finny's reality, Gene can forget about his impending enlistment at the end of his senior year for a while and be happy. Once Finny's leg breaks a second time, however, he finally admits to Gene why he pretended the war wasn't on:
I'll hate it everywhere if I'm not in this war! Why do you think I kept saying there wasn't any war all winter? I was going to keep on saying it until two seconds after I got a letter from Ottawa or Chungking or some place saying, 'Yes, you can enlist with us' (190).
For two high school seniors who face a war at the end of graduation, life seems stressful and unpredictable. Therefore, by deceiving themselves about reality, Phineas and Gene find a separate peace away from the war. As a result, they are able to be boys for a little while before having to face the truth.