大毘盧遮那成佛經疏 6.153

6.153

When the sūtra says, "If one cultivates such practice, marvelous wisdom is profoundly immovable," if one strictly preserves the authentic original text, it should say that wisdom is exceedingly profound and immovable, like the heart of the great ocean. Because it is exceedingly deep and vast, and furthermore because it is exceedingly free from the two extremes, even when great winds arise, it cannot be shaken. When the practitioner enters the heart of this great ocean of mantras, it is also just like this: because marvelous wisdom is unfathomably profound and boundless, and furthermore because it is exceedingly free from the two extremes, all phenomena cannot shake it. Just as the dragon king Sāgara sends down rain upon the six heavens, yet at that time his own three karmas remain entirely without movement in his own palace. If one understands this meaning, then one knows that the various upāyas of the maṇḍala all abide in the ultimate reality.