In The New Yorker, (5/15/95) Sara Mosle recounts that on March 18, 1937, a spark ignited a cloud of natural gas that had accumulated in the basement of the London, Texas, school. The blast killed 293 people, most of them children.

The explosion happened because the local school board wanted to cut heating costs. Natural gas, the by-product of petroleum extraction, was siphoned from a neighboring oil company's pipeline to fuel the building's furnace free of charge.

London never recovered from the blast that turned the phrase "boom town" into a bitter joke. The one positive effect of this disastrous event was government regulation requiring companies to add an odorant to natural gas. The distinctive aroma is now so familiar that we often forget natural gas is naturally odorless.

There is a tendency these days to classify all feelings of guilt as hazardous to our self-esteem. In reality, guilt can be valuable, an "odorant" that warns us of danger.