What Are the Locations of the Eight Consciousnesses in the Physical Body?

The eight consciousnesses are formless and without appearance; they are not material form (rūpa-dharma). Between the consciousnesses and material form there is no physical kind of contact, and therefore the consciousnesses are not located inside, outside, or in between the material form of the physical body. If the consciousnesses were inside the physical body, then by taking apart the material form of the body, cutting it open piece by piece, one would be able to see the consciousnesses. But even if the body were chopped entirely to pieces, no consciousness would be seen running out; even if the supreme faculty (indriya) at the back of the head were taken apart, the eight consciousnesses could not be found. Therefore the consciousnesses are not inside the physical body.

If the consciousnesses were outside the physical body, outside the body is empty space, and the consciousnesses cannot be in empty space; they are of two different natures and cannot exist within each other. Even if the consciousnesses were in empty space, they would have nothing to do with you — they would be consciousnesses belonging to no one, and they could not be shared by everyone. If the consciousnesses were on someone else's body, they would belong to that other person; if they were on insentient objects, smashing the objects would reveal nothing. Therefore the consciousnesses are not outside the physical body.

If the consciousnesses were in the middle of the physical body, no location for such a "middle" can be found. If they were on the surface of the body, that still counts as inside the body, not the middle. As long as there is a location, it is inside the body, not the middle. Therefore the consciousnesses are not inside, outside, or in the middle of the physical body.

For specifics, refer to the first volume of the Śūraṅgama Sūtra, where the World-Honored One explains that the six consciousnesses are not inside, outside, or in the middle of the physical body. The seventh and eighth consciousnesses are the same as the six consciousnesses — none of them is inside, outside, or in the middle of the physical body. Material form and non-material form cannot have physical contact of that kind, so non-material form cannot be inside, outside, or in the middle of material form.

Then someone may ask: So where exactly are the eight consciousnesses? You cannot say they are nowhere at all, can you? The eight consciousnesses are of course at their respective places of function, but they are not seen with the eyes, because they are formless and without appearance. As for what specific functions each of the eight consciousnesses has, apply effort and contemplate on your own; at a certain point you will be able to realize each of the consciousnesses, and then you will know where each of them is. Among them, the first six consciousnesses are relatively easy to realize, while the seventh and eighth consciousnesses are extremely difficult, and only with fully endowed and considerable causal conditions can they be realized.