All dharmas are the nature of tathāgatagarbha

The Buddha said in the Śūraṅgama Sūtra that the brightness of daytime is not the sun's color either. Then where does the light of a flashlight come from?

In the Śūraṅgama Sūtra the Buddha said: （一切法都是）非自然性，非因缘性，皆是如来藏性。The World-Honored One deliberately gave examples to show that although the sun shines in the sky, the brightness does not come from the sun; rather, brightness is intrinsically the nature of the tathāgatagarbha. This means that the sun's shining is a surface phenomenon: there is no brightness inside the sun, and there is no brightness in empty space; yet some sentient beings with affinities can see brightness, which shows that brightness comes from the tathāgatagarbha. Brightness relies upon the sun as a condition and is produced by the tathāgatagarbha. Brightness is material form, constituted by the four great seeds of earth, water, fire, and wind. Only the tathāgatagarbha contains the four great seeds and can form brightness; the sun and empty space have no four great seeds and cannot produce brightness. Therefore brightness is precisely the nature of the tathāgatagarbha.

By the same reasoning, the light of a flashlight does not come from the flashlight itself; it relies upon the flashlight as a condition and is produced by the tathāgatagarbha. This light is also constituted by the four great seeds of earth, water, fire, and wind. There are no four great seeds inside the flashlight, and there are no four great seeds in empty space; the light can only be formed by the tathāgatagarbha and comes from the tathāgatagarbha. On the surface, the myriad things appear to be generated by some thing, but in fact Nāgārjuna Bodhisattva says in the Madhyamaka śāstra: 诸法不自生，也不从他生，也不无因生。This indicates that all are produced by the tathāgatagarbha; this is the realized content of the wisdom of the varieties of paths of post-bhūmi bodhisattvas.

For example, on the surface grass and trees appear to be produced from the seeds of grass and trees, but in fact the seeds of grass and trees are also produced by the tathāgatagarbha. The seeds of grass and trees have no self-existing existence, and therefore cannot further produce other dharmas, because they lack the four great seeds. Grass and trees are not directly born from the seeds of grass and trees; rather, relying upon those seeds, they are brought forth by the tathāgatagarbha. Seeds producing grass and trees is a surface illusion; in reality, all are produced by the tathāgatagarbha using the four great seeds. It is like a child who, on the surface, appears to be born of the parents, but is in fact born from his own tathāgatagarbha.

Take another example: tables, chairs, and benches, on the surface, seem to be made and generated from wooden boards, but in reality they are formed by the four great seeds of the tathāgatagarbha. The wooden boards are also generated by the four great seeds of the tathāgatagarbha. That which is produced has no self-nature and thus cannot give birth to other dharmas. Again, a house seems to be generated from the combination of bricks, tiles, and earth, but in reality it is formed by the four great seeds of the tathāgatagarbha and is brought forth by the tathāgatagarbha. Including the various materials that make up the house, all are generated by the four great seeds of the tathāgatagarbha; all are the nature of the tathāgatagarbha. The formation of all dharmas, from beginning to end, must ultimately be traced back to the tathāgatagarbha. Then there is not the slightest error, and it accords with the truth spoken by the World-Honored One that all is the nature of the tathāgatagarbha. Such a person is a true son of the Buddha, not of the lineage of the non-Buddhists.

This world, that world—no matter what world it is; this thing, that thing—no matter what thing it is, all are directly transformed and fashioned by the tathāgatagarbha. But the merit does not all belong to the tathāgatagarbha alone; the manas has a share in it. If not for the manas's intentional attention (manaskāra) and deliberation, the tathāgatagarbha could do nothing about it; no matter how many abilities He possesses, He would have no means to employ. This first transformative consciousness (parināma) and the second transformative consciousness together and in harmony evolve all the myriad dharmas. The tathāgatagarbha knows the mental activities of the manas, being selfless and without self; the manas, however, grabs all the credit for itself—"me, me, me"—like a thief stealing another's wealth. Nor can the third transformative consciousness be absent here: the mind consciousness constantly schemes and plans, analyzes and reasons about what would benefit itself, and then informs the manas, offering strategies and counsel. The manas, having learned of it, deliberates without cease, finally makes the decision, the six consciousnesses execute it, and in the end the result is enjoyed by the manas. The tathāgatagarbha stands outside the circle, watching all of this as if it had nothing to do with Himself—truly a master of tranquility (praśama).