How can we determine the main idea in a piece of writing? What are some things to look for when determining the main idea?

In the sweet hereafter and the following poem, what does the newborn symbolize? "every death is magic from the enemy to be avenged" by brooks haxton when fever burned the last light out of my daughter's eyes, i swore to find and kill the ones to blame. men must mount the long boat in the dark with spears. at dawn, where the flowering spicebush hid my scent, i crouched. a young wife, newborn slung across her chest, came first for spring water. she stooped. my god, for vengeance, spoke her secret name inside my ear. her god stepped back with no scream, his right hand at his mouth, the knuckles clenched between the pointed teeth. death is not evil. innocence of childhood the continuing cycle of life and death the children that will never be born