To: You,

Take a minute, for example, to make a list of all the people you know whose death would leave you truly devastated. Chances are you will come up with around 12 names. That, at least, is the average answer that most people give to that question. Those names make up what psychologists call our sympathy group. Why aren’t groups any larger? Partly it’s a question of time. If you look at the names on your sympathy list, they are probably the people whom you devote the most attention to — either on the telephone, in person, or thinking and worrying about. If your list was twice as long, if it had 30 names on it, and, as a result, you spent only half as much time with everyone on it, would you still be as close with everyone? Probably not. To be someone’s best friend requires a minimum investment of time. More than that, though, it takes emotional energy. Caring about someone deeply is exhausting. At a certain point, at somewhere between 10 and 15 people, we begin to overload, just as we begin to overload when we have to distinguish between too many tones. It’s a fuction of the way humans are constructed.

From: Me.

The Tipping Point by Malcolm Gladwell