Dear Dr. Boli: Every time I go to the market, I see a sign: “Caution Automatic Door.” I’ve cautioned these doors for many months now—but my warnings are ignored. Is there some special danger these doors face? —Sincerely John M.

Dear Sir: You do not give yourself enough credit. The gossip columns and police blotters are full of the activities of automatic doors that have been indiscreet or worse, and yet the doors you mention have been quietly doing their job for as long as you have been warning them. Doubtless the opportunity has arisen many times to slam shut on some young woman’s skirt and have an ill-natured laugh at her expense, or to refuse to open when the manager comes in at 8:30. But whenever those occasions present themselves, the doors call to mind your cautions, and the cautions of the countless other anonymous good citizens who have taken the trouble to follow the instructions on the sign. Who can say what trouble those doors might be in at this very moment, were it not for your timely admonitions, delivered regularly and always in a spirit of charity? Well done, sir. And since you have shown evidence of such exemplary public-spiritedness, Dr. Boli ventures to suggest another field in which your endeavors might prove valuable. Do you think you might be able to do something about the slow children on Bland Street? The sign warning that they are just ahead has been there for years now. Obviously they must pose a danger to vehicular traffic, or there would be no sign. Can nothing be done to disperse them?