成唯識論演祕 6.509

6.509

詳曰：大乘初生唯第八識，今云意識有違宗過。今助一釋，理實結生是第八識，據後相續容有六識，故說有六識。

Examination: In the Mahāyāna, initial birth is solely the eighth consciousness; saying now that it is mental consciousness incurs the fault of contradicting the tenets. Now, to support with an explanation: in truth, linking to rebirth is the eighth consciousness; in terms of subsequent continuity it can allow the six consciousnesses, and therefore it is said that there are six consciousnesses.