"If you say in the first chapter that there is a rifle hanging on the wall, in the second or third chapter it absolutely must go off. If it's not going to be fired, it shouldn't be hanging there."
1. Time & Place (physical environment)
2. Grapes of Wrath
For example: Greasy Lake, The Storm,Time
iv. Day of Week
v. Time of Day
vi. General Era
Place (physical environment)