GUIDANCE         “Is it worth the trouble?” and “Is it worth the money” register at the same existential spot in our soul. We measure the return on our investment of time and effort in a friendship in much the same way we measure the return on investment of our money. A social relationship can be rewarding or can be draining, for instance. Another such phrase: extend ourselves. There are fair-weather friends and there are fair-weather purchases. There are people we go to a lot of trouble for, an...