五音六律

Explanation: Pentameter refers to the gong, shang, jiao, zhi, Yu five scales; six legal instruments _set_ the standard. ◇ also refers to an ancient musical temperament. 　　Source: "Shangshu Yi Ji" I like to hear six-laws, five sound, octave, suddenly in the rule; the cashier Wu Yan, Yu listening. "" Lou on Mengzi, "not to six law, not being pentameter."