大方廣佛華嚴經疏 44.16

44.16

Now first, within the virtue of cultivating practice, there are the Dharma, the simile, and the correlation. In the Dharma, beginning from Joyous and ending at Cloud of Dharma is called the progressive practice-characteristics. Once the progression is complete, one enters the ocean of wisdom. In the simile, the four great rivers issue each from one side, fully as in the 'Chapter on the Ten Samādhis'. That they are called 'great' is because the Āgama and the Vibhāṣā state that twenty rivers emerge: forty li from the lake, each of the four rivers divides into four, which together with the original four make twenty. Here, referring to the original rivers, they are therefore called 'great'; below, 'expanding and increasing' subsumes the remaining sixteen. And that the Śrīmālā speaks of eight is because all people fully see the five rivers on the eastern side, and the fame of the other three great rivers is widely heard, whereas the twelve small rivers are neither heard nor seen; hence it speaks only of eight. In the correlation, the bodhicitta correlates to the lake flowing forth, and the roots of goodness and the like correlate to the four rivers. Relying on bodhicitta, one cultivates the practices of the four means of embracing, and one's own good increases. According to the 'Chapter on the Ten Samādhis', four rivers are expounded, which the present text embraces: first, the river of wisdom of vows, which is the water of the great vows; second, the river of pāramitās; third, the river of samādhis, which is the present roots of goodness; fourth, the river of great compassion, which is filling sentient beings by means of the four dharmas of embracing. Saying 'without exhaustion' and so forth correlates to the unexhausted depletion above; the great vows and the like are all inexhaustible.