Adam Schall could stay in China, because he served at the court as astronomer. We must remember that his status as missionary was yet unstable. As he mentioned in his Memoir, it was very difficult to send the missionaries to Korea, for the Manchu prevented the people from penetrating Korea, and all Koreans who had entered China were numbered one by one and should return by the same number.
If we take parts of Memoir without filtering, we might falsify the reality. Because the letter written by Prince Sohyeon is not extant, we cannot judge whether it was authentic or not. Even if the Prince wrote the letter, Adam Schall did not cite the letter honestly. Rather we believe that Adam Schall expressed his own wish through the mouth of the Prince. We cannot confirm any other fact than the acquaintance of Prince with Adam Schall.
On return the Prince was accompanied by the Chinese eunuchs and court ladies; but when we consider the political situation, it was impossible that they were sent by Adam Schall for the missions. Besides we don"t know what role they played in Korea.
Therefore we cannot regard Prince Sohyeon as semi-Christian or cannot assert that he accompanied the Chinese baptized eunuchs instead of missionaries. Some writer said that with the death of Prince Sohyeon the dream of Adam Schall of the Korean missions disappeared; but it was impossible in the context of the reality of that time. We cannot maintain only on the basis of the fact that the Prince met Adam Schall, that Prince Sohyeon became semi-Christian or that if he would become king, then Korea could be christianized easily. The acquaintance of the Prince with Adam Schall was one episode in the Korean history, and when the Prince died, the fact itself was forgotten. We cannot find in the Korean official documents any reference indicating that acquaintance. Therefore new documents need be found.
On the other side, as Adam Schall laid stress on his own friendship with Emperor Shun-Zhi, so faithful to the policy of evangelisation from the top down, he laid stress on his acquaintance with Prince Sohyeon, and wrote that he would get the opportunity to evangelize Korea, the unknown country in the Far East. But as the trial to evangelize Emperor Shun-Zhi could not be realized, so the dream to evangelize Korea could not be realized. Nevertheless he exaggerated the trial to evangelize the Korean prince.