Where in the physical body are the eight consciousnesses located?

The eight consciousnesses are formless and without appearance; they are not material form (rūpa-dharma). Between them and material form there is no physical kind of contact. 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 body—this material form—cutting it open piece by piece, one should be able to see the consciousnesses. But even if the body were chopped entirely to pieces, no consciousness would be seen to come out; even if the supreme faculty (rūpa-prasāda) 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, then outside the body is empty space, and the consciousnesses cannot exist within empty space, for they and empty space 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 another person, they would belong to that 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 in the 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 the physical kind of contact, 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? Surely you cannot say they are nowhere at all? The eight consciousnesses are of course at their respective places of function, but they cannot be 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; when the time comes, 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; only with fully endowed and considerable causal conditions can they be realized.