仁王護國般若波羅蜜多經疏 2.475

2.475

解曰：不可說識者，此有二義。有說：本識從初結生一期壽命，乃至最後剎那滅識，於二中間剎那不住，識之生滅不可說也。舉其邊者，如有頂地及無間中，從初至後有不可說，況於長劫豈可說業乎？有說：業識從初起後、至末斷前，然於中間無始生滅造業受果，於界趣生、從心生心，染淨諸識剎那相續皆不可說，故經重云不可說矣。從此第二從心生色。

Exposition: 'Inexpressible consciousnesses' has two meanings. One explanation says: from the initial linking of birth for a single lifetime, up to the final moment of the ceasing consciousness, the fundamental consciousness does not abide for a single moment in between; the arising and ceasing of consciousness is inexpressible. To mention its extremes: as in the Peak of Existence (bhavāgra) and within the Avīci [Hell], from beginning to end there are inexpressible [moments], so how much less can one express the karma throughout long kalpas? Another explanation says: from when the karmic consciousness first arises to its later [states], up to when it severs the former at the end, during the interval throughout beginningless arising and ceasing it creates karma and experiences fruits; within the realms, destinies, and births, mind produces mind, and the moment-to-moment continuation of all defiled and pure consciousnesses is entirely inexpressible. Hence the sūtra repeats 'inexpressible.' From this point, the second [part clarifies] mind producing matter.