resulted. Mercantile activities rapidly increased in volume. The accumulation of capital through monopoly and wholesales expanded through guild organisations and many merchants were centred in Hanseong. The traditional division of government chartered shop, the license tribute goods suppliers and the small shopkeepers in the alley and streets were integrated and woven into a monopoly and wholesale system. Regardless of status, many yangban aristocrats and commoners engaged in some kind of merchant activities. Thus Hanseong made great strides as a commercial and industrial city in the 18th century. The popular demand for handicrafts and goods such as knives, horse hair hats, dining tables and brassware was ever-increasing. Restrictions on wearing the horse hair hat originally denoting yangban status, virtually disappeared. Even bootlegging of books became commercialised as competition developed among the well-to-do yangban who engaged in the publication of collected literary works by their renowned ancestors. This also led to printing popular fiction and poetry. The people especially appreciated satire and social criticism. One example is the Chunhyangjeon (Tales of Chunghyang) about the fidelity of the gisaeng's daughter, which was widely read as a satire aimed to expose the greed and snobbery of government officials. Anti-corruption The King is also renowned for having treasured Park Mun-su, whom he appointed as secret royal inspector (Amhaengeosa; 암행어사). Park, who had earned great merit in putting down Yi In-jwa's rebellion in 1728, went around the nation arresting corrupt local officers in the name of the King. Controversy The only significantly dismal incident during Yeongjo's reign was the death of his son, Crown Prince Sado. History indicates Sado suffered from mental illness; randomly killing people in the palace and raping palace maids. Because Yeongjo could not execute his son without also implicating his daughter-in-law and beloved grandson, he ordered the Sado to climb into a wooden rice chest on a hot July day in 1762. After eight days, Sado died. During the 19th century, there were rumors that Crown Prince Sado had not been mentally ill, but had been victimised by a court plot; however, this is contradicted by both the memoirs written by Sado's widow and the Annals of the Joseon Dynasty. As a means to preserve the legitimacy of Sado's son as his own heir, Yeongjo decreed that the boy be registered as the son of the deceased Crown Prince Hyojang and Crown Princess Consort Hyosun. Catholicism Yeongjo was the first to take