of course , someone has to break this cardinal rule , or no one would arrive at all , but a new shop is apt to stand empty for at least twenty minutes after the closed sign in the window has been turned over to read open for the first time , and a knowledgeable observer would feel safe in wagering that the first arrivals would come in a group-a pair , a trio , but more likely a foursome of ladies the second rule is that the investigating shoppers display a politeness so complete that it verges on iciness .