Dear Dr. Boli: Where does dust come from? I clean everything to a spotless shine. I vacuum three hours a day and change vacuum bags in my special sealed vacuum bag changing room. Yet dust still appears within hours. Where does it come from? —Sincerely, Martha Stewart (name withheld by request).

Dear Madam: Many theories have been advanced to account for the apparently unaccountable appearance of dust on clean surfaces, and especially on wooden surfaces. Some theoretical physicists account for it as a natural by-product of the atomic decay of wood, which produces tiny thread-like particles called “strings.” Some theologians, noting that dust is specifically mentioned in the curses at the end of the Fall narrative (Gen. 3:19), believe that the dust on your furniture is made up of microscopic fragments of Adam, which must remain with all of his descendants until the final resurrection. But the most plausible theory is that dust is planted by enemy agents bent on subverting the clean American way of life. Whenever you have visitors in your house, examine your furniture carefully after they have left to see whether there is any more dust than before. If there is, report those visitors to the Department of Homeland Security, Bureau of Dust Prevention. You will be doing your part to preserve the American way.