The nation gazed wistfully at high school sophomore Eliza Baker as she took notes in a dog-eared copy of Harper Lees To Kill A Mockingbird at a municipal bus stop Thursday. What pure, tender joynot to have a care in the world beyond identifying themes in a classic American novel, said bystander Jeanne Copley, 24, adding that she envied the 15-year-olds seeming engrossment in the book and the unrestrained eagerness with which the girl turned from one page to the next. I think I just saw her write Scout = American Dream? in the margin. Ah, I just want to tell her to cherish this moment. Cherish every last precious second of it while you still can. Sources said Baker later wrote an emotionally laden breakup letter to her boyfriend of two weeks, hurtling the nation into a rapturous fit of fond reverie. 