Before the first Opium War, the Chinese believed to be absolutely superior over all "Barbarians". The Chinese had always viewed that they were the Heaven's favorite, as their emperor was chosen by the Heavens. They were the Middle Kingdom, at the center of the earth. Whenever any other nation came to visit, it was to pay tribute to the mighty emperor; thus, the Tribute System was implemented, and foreigners had to kowtow to the emperor. Obviously, the Chinese were above these barbarians who all seemed to be of the merchant class, the class most despised by Confucian ideals. But, they were given the strictly regulated Ports of Macau and Canton. The only time the people of the West was given a smidgeon of respect was when they presented astronomy and mathematics related advancements. However, it was not that the Chinese were behind in their knowledge, but it was the Chinese who had originally thought of all of these brilliant ideas and had given them to the West, thus maintaining Chinese superiority. As long as the people of the West followed the Chinese rules, and remained inferior, the contact was rather successful. However, the second the Pope started to impose himself on the nation (around 1715), Yongzheng prohibited Christianity, and by 1724, the intensive contact had ended. The foreigners were only allowed to stay for practical means, which would help China. This brings us to an important point of the difference in the Chinese learning and Japanese learning of the West: the Chinese integrated their previous knowledge with the new ideas of West, whereas the Japanese completely threw out the old and replaced it with the ones of the West as in Rangaku. The Macartney Mission was the last straw for the Chinese; the insolence of Macartney was enough to poison the interchange between the two countries. Qianglong decided that there was no use West, for they were only in China to show tribute.