Tongue and Tooth
The location where the Twin Towers were located is distinct. While on the flight, "Jane and Bruce can't help but locate the spot where the Twin Towers used to be, the same way the tongue finds the hole where a tooth was pulled. " Being on the plane places them in a vantage position to identify the location, which cannot be forgotten. At the time of the towers' falling, their children were infants who had no clue what was going on. The place is like a tooth hole that a tongue cannot forget.
Small Birds
Crispin uses a wheelchair at every point. His vulnerability and bad health are evident. Napolitano describes, "Occasionally, his fingers flutter, like small birds struggling to take flight." Being in bad health warrants that he is with a nurse that can help him with his locomotion. The fingers' fluttering is a signal of the pain that he is experiencing. Nonetheless, he must complete the flight. Crispin's struggles differ from those of the passengers on the plane with him.
Grenades
Fatherhood is so demanding for Bruce that it triggers his migraines. Bruce likens his sons to grenades because of the pressure he faces once they are born. Napolitano illustrates, "When the boys were babies, Jane used to say that he carried them like live grenades." Bruce holds the same view even after the boys become teens because parenting them is very sensitive. Fathering young boys who could disappear from the house anytime can be strenuous for any parent. Bruce prefers to have them under his watch because they could still explode like grenades.
