How did Mr. and Mrs. Morrison deal with their emotions over Luke's happy news?

Katie recalls how happy her parents were even though they did not demonstrate this emotion. The Morrisons had an unwritten rule restricting the display of emotions. They began immediately to discuss practical things, such as what Luke would need for school, even though there were several months before he would be leaving. The parents decide that Luke will need a suitcase and so they go into the city the following day.