The expression was first used in poetry criticism to mean that a poem fully met poetic stylistic standards. It later became an important term in Chinese classical operatic theory. It has two meanings. One is that the language used by a character in a play is simple, natural, easy to understand, and appropriate for the character. The other is that characters and plot of the play are true to life with a strong artistic attraction. In Ming-dynasty operatic theory, “professionalism”and “being true to life” are often used together to describe outstanding opera works.
Beginning in the Yuan Dynasty, professional simplicity, rather than flowery rhetoric, has gained popularity as an operatic style. (Ling Mengchu: Miscellaneous Notes on Opera)
Professional actors can play their roles so vividly as if they were the characters themselves, forgetting that the story is fictional. Their performances can make viewers so happy that their beards will fly up, or make them so angry that they will wring their wrists, or make them so sad that they will sob, or inspire them so much that they will become thrilled. Only artists like Youmeng can create such effect. Therefore, for an opera to be outstanding, it first and foremost must be professional. (Zang Maoxun: Second Foreword to Selected Works of Yuan Opera)