In the 1930s, twice a week a Frenchman crossed the frontier into Germany on his bicycle carrying nothing but a suitcase filled with sand. The German customs officers, sure that he was smuggling something - money, drugs, jewellery, watches - examined the case and its contents thoroughly. But they could find nothing but sand. This went on for a year or more, and they found nothing in all that time. Always he had nothing on his person, and the case held nothing but sand. Eventually he stopped, and some time later they discovered that he had been smuggling - bicycles!! And if this is not a true story, it ought to be.