 The earliest converts to Catholicism were all Confucian-trained scholars from aristocratic (yangban) families. Yi Pyŏk (1754–1786), as well as Yi Sŭnghun (1756–1801), were the leaders of this group who were soon joined by other yangban scholars, such as the two Kwŏn brothers (including the son-in-law of An Chŏngbok), and the three Chŏng brothers. The youngest of the Chŏng brothers, Yagyong (1762–1836), more generally known by his penname Tasan (often written as Dasan), is one of the most widely acclaimed philosophers in Korea’s intellectual history, discussed below. His early Confucian mentor, Yi Pyŏk, wrote the first lengthy outline of Christian doctrine in Korea, Sŏnggyo yoji (聖敎要旨) [The Essence of the Divine Doctrine] in Classical Chinese for his “Confucian” entourage. However, his hymn, Ch’ŏnju konggyŏng-ga (천주공경가) [Hymn in Adoration of God], is considered one of the first hymns written in Han’gŭl, the vernacular script, which was first promulgated in the fifteenth century, though generally associated with women and men from the poorer classes. In fact, so poorly was this simplified script esteemed in elite circles that it was referred to as Ŏnmun (諺文), meaning the vulgar script. But Yi’s hymn was also deeply Confucian, advocating loyalty to the king, emphasising filial piety, and even encouraging adherence to the “Five Relationships”. This Confucian aspect of early Catholicism reflects an interesting transcultural interaction between both traditions, highlighting their moral priorities. Chŏng Yakchŏn (1758–1816) and Chŏng Yakchong (1760–1801), also wrote Catholic texts in Han’gŭl, which also exhort Confucian morality: loyalty to the king, as well as filial piety, tropes already found in Yi’s hymn. In fact, in Chŏng Yakchŏn’s Sipkyemyŏng-ga (십계명가) [Hymn in Praise of the Ten Commandments], he writes that “Among all the things in the world, filial piety is the most important”, which also clarifies the singular importance of filial piety in Korean Confucianism (Ha (ed.) 2000: 334). Chŏng Yakchong wrote a much longer treatise on Catholicism in Han’gŭl, called Chugyo yoji (주교요지) [The Essence of The Lord’s Teachings], obviously directed at a growing audience who were not yangban scholars. In fact, many were women and members of the lower classes, overturning and destabilising entrenched hierarchical Confucian social norms, while at the same time advocating Confucian morality, but supplemented with egalitarian Christian ideas (Cawley 2015).