Wooreuk, Gaya's great master of music, who had realized the desperate situation of the fatherland, expatriated himself, along with his disciple Yimoon, to King Jinheung of Silla in 551(12th year of his reign). As he voluntarily became a citizen of Silla 11 years before Gaya's conquest by King Jinheung, he was treated with warm hospitality by King Jinheung and was later enshrined in Kookwon(國原), now Choongju.
King Jinheung sent 3 Silla bureaucrats to Wooreuk to master his 12 musical pieces but they criticized them as too complicated and lascivious and adapted them into 5 musical pieces. Wooreuk was at first very outraged with his Silla disciples' arbitrary adaptations but, after appreciating the adapted musical pieces, repented of his musical pursuit away from Confucian virtues. King Jinheung accommodated these 5 adapted musical pieces into Silla's "Daeak(大樂)", providing a musical-historically important opportunity that Wooreuk's gayageum(a twelve-stringed harp) music, which could have disappeared with the fall of Gaya, can be passed on till today.
Silla bureaucrats' pursuit of Virtuous Music can be seen both from their critical view of Wooreuk's 12 musical pieces that were composed at the order of King Gasil of Gaya and from Wooreuk's reaction to his Silla disciples' dealings with his musical pieces.
Wooreuk deeply regretted his early invirtuous musical inclination and professed his true musical view "Nakibullew, Aeibulbi(樂而不流, 哀而不悲)", which is construed as the same as "Nakibuleum, Aeibulsang(樂而不淫, 哀而不傷)" in Sigyung(詩經 the Book of Odes).
His thought of music is a practice of Virtuous Music, the Confucian view of music, which is in complete conformity with the historical fact that the Confucian culture was already in place in Silla and Gaya in the Three-Kingdom Period.
Virtuous Music here indicates court music which requires Ye(禮 Etiquette). The music pursued by Wooreuk is Etiquette Music(禮樂) where Etiquette and music interact with each other.