Bright Mirror Lake.
Celestial Academy, since the demise of the Mitian Sect, has witnessed unprecedented progress, elevating its century-old reputation and status at Bright Mirror Lake significantly. Now at Bright Mirror Lake, the dream destination for cultivators with talent is almost always Celestial Academy. However, within Celestial Academy, regardless of your talent, if you're below the Profound Realm, you can only cultivate in the Outer Courtyard. Only by stepping into the Profound Realm can you enter the Inner Courtyard.
Hence, the ratio of Inner Courtyard to Outer Courtyard is 1 to 1000.
