We have seen, in this book, how a number of relatively minor changes in our external environment can have a dramatic effect on how we behave and who we are. Clean up graffiti and all of a sudden people who would otherwise commit crimes suddenly don’t. Tell a seminarian that he has to hurry and all of a sudden he starts to ignore bystanders in obvious distress. The Rule of 150 suggests that the size of a group is another one of those subtle contextual factors that can make a big difference.
