The Distinction and Boundary Between the Inner Six Dhātus and the Outer Six Dhātus

What the six consciousnesses perceive is the inner six realms; the outer six realms cannot be perceived. The outer six realms are composed of the real four great elements and the seeds of the five great elements; they are real material form, the essential-object realm (本質境), and this portion of material form corresponds only to the tathāgatagarbha. The inner six realms, however, are the realm of bearing substance (帶質境), not the most real material form; they are realm-form that carries the substance of the outer six realms and the seeds of the five great elements, and are no longer the original substantial material form—like an image in a mirror: although the shape is similar, it can no longer be touched. What can be touched is substantial material form; what is similar and false, which cannot be touched, is only empty and therefore has no practical use. 

Since what the six consciousnesses perceive is false dharma without practical use, why do sentient beings use it every day? In fact, sentient beings do not truly use it either; the so-called use is only sensation. Sensation is illusory, and what is sensed is also illusory. This hurdle is very hard to get past; only after personally realizing emptiness (śūnyatā) can one see through it. 

Then where is the boundary between the inner six realms and the outer six realms? After the tathāgatagarbha initially transforms and produces the six realms by means of the seeds of the five great elements, the manas relies on the tathāgatagarbha to perceive dharmas. But what the manas perceives differs from what the tathāgatagarbha perceives: the marks perceived by the manas are material form bearing the appearance of the mundane world, belonging to mundane dharma, whereas what the tathāgatagarbha perceives is not mundane dharma and has no mundane appearance—this part sentient beings simply cannot understand. After the manas perceives the dharmas, the tathāgatagarbha continues to transmit them into the supreme faculty (indriya). During this transmission, the material form is constantly arising, ceasing, and changing, until it arrives within the supreme faculty; what the six consciousnesses perceive is then no longer the six realms outside the supreme faculty. The six realms begin to change as soon as the manas perceives them; by the time the six consciousnesses perceive them after the manas has done so, they are no longer receiving the original six realms.

In this way, the six realms are roughly divided into three levels: first, what the tathāgatagarbha perceives; second, what the manas perceives; third, what the six consciousnesses perceive. The further along the six realms go, the less substance they carry, the greater their transformation, the more they are altered, and the more false and unreal they become—just like what is reflected through three layers of mirrors. When the solitary consciousness (mano-vijñāna-eka-citta) further recollects, fantasizes, and compares within the mind, that realm no longer has even a bit of substance. After the six consciousnesses make discriminations about these various images, the arising of thoughts affects the manas; the manas then stirs thoughts, which affect the tathāgatagarbha; and if the karmic seeds allow, the essential-object realm of the outer six realms will be changed. Once the outer six realms change, the inner six realms that arise in accordance with them will change accordingly, and the world will take on a different appearance. If the six consciousnesses do not discriminate about these layered images and remain unmoved by them, what will the result be?