大方廣佛華嚴經隨疏演義鈔 76.8

76.8

疏「一以油水對上日月為水月喻」者，則日月喻菩薩悲智，水喻機心。水中之月喻定地境界，謂定中見佛等。亦喻遍處，定境青黃赤白等故。〈出現〉偈云「譬如淨月在虛空，能蔽眾星示盈缺。一切水中皆現影，諸有觀瞻悉對前。如來淨月亦復然，能蔽餘乘示修短，普現人天淨心水，一切皆謂對其前。」叡公云：「水月不真，唯有虛影。人亦如是，終莫之領，為之驅驅，背此真淨。若能悟之，超然獨醒。」

Regarding the commentary's "First, matching oil and water against the sun and moon above constitutes the water-and-moon metaphor": the sun and moon illustrate the bodhisattva's compassion and wisdom, while the water illustrates the mind of the receptive beings. The moon in the water illustrates the realm of the state of meditative absorption (samādhi), meaning seeing the Buddha within absorption and so on. It also illustrates the kasina-spheres (kṛtsnāyatana), because the realms of absorption are blue, yellow, red, white, and so on. The verse in the "Appearance" chapter says: "Just like the pure moon in empty space, / Able to outshine the host of stars and show waxing and waning, / Casting reflections in all waters, / Appearing right before all who look upon it: / The pure moon of the Tathāgata is also like this, / Able to outshine the other vehicles and show long and short life, / Universally appearing in the pure mind-water of humans and devas, / So that all say he is right before them." Master Sengrui said: "The moon in the water is not real, there is only an empty reflection. People are also like this, never grasping it; toiling busily for it, turning their backs on this true purity. If one can awaken to this, one awakens alone, transcendent."