Read the excerpt from “The Scarlet Ibis.” There is within me (and with sadness I have watched it in others) a knot of cruelty borne by the stream of love, much as our blood sometimes bears the seed of our destruction, and at times I was mean to Doodle. One day I took him up to the barn loft and showed him his casket, telling him how we all had believed he would die. It was covered with a film of Paris green sprinkled to kill the rats, and screech owls had built a nest inside it. Doodle studied the mahogany box for a long time, then said, “It’s not mine.” “It is,” I said. “And before I’ll help you down from the loft, you’re going to have to touch it.” What symbol is described in this excerpt, and what does it represent?