According to his assessment, nationalist emotions were running high in the 18th and 19th centuries, so people were inclined to oppose anyone having divided loyalties. But in the past few decades, with the development of the global economy, contacts between nations have multiplied, and many people have a real need to travel frequently between countries for economic or cultural reasons not necessarily related to politics.
據他的分析，十八、十九世紀時，民族主義發達；但近幾十年，工商業興盛、國與國之間往來頻繁，很多人不是為政治，而是經濟、文化等因素，必須在幾個國家間往來。