大乘起信論廣釋卷第三．四．五 4.141

4.141

[Treatise:] Therefore, all [dharmas from the beginning are neither form nor mind, neither prajñā nor consciousness, neither existent nor non-existent, and are ultimately] characteristics that cannot be spoken of—
[Commentary:] "Explication": This adduces broad categories to examine them. Because defilement and purity are provisionally relative as mentioned before, all dharmas originally lack self-nature, and it is not only upon awakening that this is decided to be so. Hence it says, "Therefore, from the beginning...", and so forth. Mind and object are established relative to each other as form and mind. Since the two graspings are non-existent, how could form and mind exist? Saying "neither form" is because it is not what is grasped; saying "nor mind" is because it is not that which grasps. "Neither prajñā nor consciousness" clarifies the above "nor mind"; consciousness and prajñā are established relative to defilement and purity of mind. Since mind is not mind, it is therefore neither consciousness nor prajñā. "Neither existent nor non-existent" clarifies the above "neither form"; existence and non-existence depend on the arising and ceasing of form. Since form is not form, it is therefore neither existent nor non-existent. Because of this, it is ultimately unspeakable.