"Katie had the same hardships as Johnny and was nineteen, two years younger. It might be said that she, too, was doomed. Her life, too, was over before it began. But there the similarity ended. Johnnyknew he was doomed and accepted it. Katie wouldn't accept it. She started a new life where her old one left off. She exchanged her tenderness for capability. She gave up her dreams and took over hard realities in their place.
Katie had a fierce desire for survival which made her a fighter. Johnny had a hankering after immortality which made him a useless dreamer. And that was the great difficulty between these two who loved each other so well."

From A Tree Grows in Brooklyn by Betty Smith