The admonition Cave Canem (Beware of the Dog), which greeted visitors to homes in ancient Rome, should have been well-heeded by the French in August of 2003 when the heat wave struck. Egyptian astronomers were the first to discover that the disappearance of the canine constellation Sirius at night marks the onslaught of summer. As the English wit Noel Coward observed, “Only mad dogs and Englishmen go out in the midday sun.” Of course, when Sirius reappears for star-gazers at the end of August, you can bet that other Europeans will venture out too.