The nature of water is true emptiness (śūnyatā); the nature of emptiness is true water.

In the Śūraṅgama Sūtra it is said that "the nature of water is true emptiness, and the nature of emptiness is true water." Here, water refers to water that has already been generated from the water-element seed, including water particles and the water in rivers, lakes, and seas. The substance of this water is composed of water particles; the particles are constituted by the water element. The water element is a seed intrinsically existing in the tathāgatagarbha, belonging to the tathāgatagarbha, and its nature is also the nature of the tathāgatagarbha. Therefore, all water constituted by the water element is in substance of the nature of the tathāgatagarbha. What is the nature of the tathāgatagarbha? The tathāgatagarbha is emptiness (śūnyatā), empty all the way through, without any dharma whatsoever; the emptier and the emptied are both completely empty, and even emptiness itself is empty—utterly clean, without a single speck of dust. Thus the nature of any water is true emptiness, and yet within emptiness there is also the true nature of water, which neither arises nor ceases. Therefore, when the tathāgatagarbha encounters conditions, it can produce water. If there were no unborn and unceasing nature of water within the tathāgatagarbha, then no matter what conditions and causes appeared, water could not be produced.

So as for our thoughts, empty them freely; freely empty away all dharmas. When you have emptied to the very end, so that there is nothing left to empty, you have arrived home—sitting in the home of the tathāgatagarbha, greatly turning the Dharma wheel. Why, when everything has been emptied and nothing remains, can one still turn the Dharma wheel? Because within the emptiness of the tathāgatagarbha there is still true earth, true water, true fire, true wind, true seeing, and true consciousness—unborn and unceasing, genuinely existing—so that when conditions are present, all dharmas can be produced. After attaining buddhahood, the power of vows does not cease, and thus the conditions do not cease; together with the unceasing seven great seeds within the tathāgatagarbha, the Tathāgata is free to turn the great Dharma wheel and deliver all suffering sentient beings.