The movie Forbidden Dream (Cheonmoon) features the relationship between King Sejong of the Joseon Dynasty and a famous inventor Jang Young-sil. The Joseon Dynasty was a thoroughly hierarchical society, but King Sejong considered Jang Young-sil’s ability more than his status and allowed him to invent a lot of scientific facilities. This friendship between the two beyond status makes many people feel warmth.
The movie Forbidden Dream opens with a historically famous event when Sejong falls off a broken carriage on his way to a rural palace. Then it shows the story of inventing the instruments for astronomical observation. In his era, astronomical observations were regarded as what the emperors of the Ming Dynasty could do. Thus, the inventions of Jang Yeong-sil drew the ire of the Ming Dynasty, and there was a great debate within the Joseon Dynasty that Jang Young-sil should be sent to Ming to avoid anger of the emperor.
Afterward, the story when the two first met is shown. Jang Young-sil is made free from his lowest status by Sejong and even given the title. Then he starts to work for him and finally succeeds in designing and producing a water clock. One night, Young-sil and Sejong have an honest conversation, looking up the sky. Jang Yeong-sil looks at the North Star and says, "That star is a star of King Sejong." Then Sejong says, “The small star next to the North Star is a star of Yeong-sil," while looking at Yeong-sil who thinks that he cannot be the owner of the star due to his status.
Afterward, the two become close friends beyond their status differences. King Sejong always wants to make the proper astronomical calendar for the people of Joseon, and Jang Young-sil helps him. When the armillary sphere is invented and the astronomical observation is conducted successfully, some of the servants are concerned about the Ming Dynasty who will be angry to learn about it. Afterward, Sejong, who is riding on a carriage inspected by Jang Young-sil, suffers minor injuries due to the carriage breaking down. Hence, Jang Young-sil is locked up for his responsibility. Sejong comes to the prison and says that he broke the carriage to suppress his enemies on purpose, and recommends that he should go and live in a places where no one knows about him. Jang Young-sil, however, feels that King Sejong chose to give up creating Hunminjeongeum, his long-cherished ambition, and falsely confesses that he conspired in order to protect the long-held dream of King Sejong. After the story about Jang Youngsil being punished, the movie ends with a saying that no record of Jang Young-sil has been handed down.
Compared with real history, we can see that the film was made quite realistically. Jang Young-sil's father is said to be an engineer of the Yuan Dynasty, who became naturalized in Joseon. However, after he was born, his father died, and his mother became a gisaeng. As a result, his son became an official servant, and as a child, he used his dexterity to make adjustments. Unlike the movie in which King Sejong selects Yeong-sil, Yeong-sil was recognized for his talent from King Taejong. Later, he invented the water clock, as in the movie, which complemented the disadvantage of the sundial that had difficulty measuring the time depending on the weather. Besides the water clock, he also created a rain gauge and the armillary sphere, which was an invention that preceded Western technology.
Afterward, King Sejong fell off from the carriage and the reason why this accident happened was not recorded. The movie suggests that the missing part of this historical record was the scene of King Sejong wanting to save Young-sil’s life, although he had to use him as a scapegoat to avoid upsetting the Ming Dynasty.
The audience's comments about the movie are various. First of all, most people acknowledge and praise the two main actors, Han Sun-kyu and Choi Min-sik, for their chemistry and acting skills. However, there are also criticisms about whether the long running time of 132 minutes and the numerous repeated presentation of the close relationship between Sejong and Jang Young-sil could have been interesting to all audiences. However, there are many positive reviews because there are few unnecessary scenes and the movie focuses on the two characters throughout the whole story.