why they called the chapter “Let Them Laugh”

The house is becoming a home again, and Mr. Craven's broken heart is on the mend. Rather than demanding silence, Craven craves laughter. He's beaming over the change is Colin and growing to love Mary.

"So is the girl," said Mrs. Medlock. "She's begun to be downright pretty since she's filled out and lost her ugly little sour look. Her hair's grown thick and healthy looking and she's got a bright color. The glummest, ill-natured little thing she used to be and now her and Master Colin laugh together like a pair of crazy young ones. Perhaps they're growing fat on that."

"Perhaps they are," said Dr. Craven. "Let them laugh."