Kunqu Opera came of age in late Ming Dynasty, but traditional repertoire that have survived into this day have lost their earliest features. The difference lies not only in the text performed-zhezi (or scenes extracted from the whole) instead of complete plays-hut also in other artistic essences embodied by those zhezi scripts, which, since the Qian [long]-jia [jing] periods of Qing Dynasty, have become "fixed repertoire" after generations of modification and ornamentation. The exquisiteness and conventions of costumes and acting styles of those plays have been praised as "Qian-Jia Tradition," "Gusu Pattern," or "Paradigmatic Kunqu." The "complete" Kunqu performed on today's stage. however, are either "selected zhezi," revisions of old scripts, or newfangled scripts that, strictly speaking, seriously deviate from the Qian-Jia tradition and do not qualify for UNESCO's Masterpieces of the Oral and Intangible Heritage of Humanity. What deserves to be treasured, promoted, and handed down in Kunqu should be its archetypes of such performative aspects as meters, footwork, phonation what constitute the "four skills and five methods" in music, acting, and singing. Ever since the Qian-Jia periods, when "fixed repertoire" with fixed titles and fixed performance types started to be staged, there has existed a unique system and tradition of Kunqu. Because the techniques of composing, singing, and acting have been recorded and published in book form, we can trace the Qian-Jia tradition even today. This paper will discuss that tradition in terms of four aspects-the repertoire, musical composition, performance principles, and diversity of schools-to illustrate the invaluable qualities of Kunqu Opera that make it worthy of the name of humanity's Masterpiece.