大乘起信論義記 3.213

3.213

In the former part, the words "relying on the differentiating empirical consciousness" mean that ordinary beings and [followers of] the two vehicles do not yet know cognition-only and posit external dust-like objects, which is the meaning of the differentiating empirical consciousness. Now seeing the Buddha's body, they also consider it to be external to the mind; conforming to that empirical consciousness's differentiation and reckoning, it is therefore said to be seen relying on the differentiating empirical consciousness. It can also be that although these people are aware of the six consciousnesses, they are not aware of the seventh and eighth consciousnesses, and therefore only rely on the empirical consciousness. Differentiating the Buddha's body in reliance on this coarse consciousness, they only see the coarse marks of the responsive transformation and do not see the subtle marks of the reward body; hence it is said, "it is called the response body." "Because they do not know that it is manifested by the evolving consciousness... unable to know it completely" explains the reason for seeing the coarse. Being deluded about mind-only, it is therefore said to "come from outside." Not comprehending that form is precisely mind and has no limits or measures, it is therefore said to "grasp the measures of forms and be unable to know it completely."