Catholic missionaries—mostly Jesuits—had arrived during the Ming dynasty. By 1701, there were 117 Catholic missionaries, and at most 300,000 converts in a population of hundreds of millions. There were many persecutions and reverses in the 18th century and by 1800 there was little help from the main supporters in France, Spain and Portugal. The impact on Chinese society was difficult to see, apart from some contributions to mathematics, astronomy and the calendar. By the 1840s, China was again becoming a major destination for Protestant and Catholic missionaries from Europe and the United States. They encountered significant opposition from local elites, who were committed to Confucianism. These elites resented Western ethical systems, which were seen as a threat to their power, and often viewed missionaries as a tool of Western imperialism. The mandarins claim to power lay in the knowledge of the Chinese classics—all government officials had to pass extremely difficult tests on Confucianism. The elite feared this might be replaced by the Bible, scientific training and Western education. In the early 20th century, the examination system was abolished by reformers who admired Western models of modernization. According to Paul Cohen, from 1860 to 1900: