成唯識論述記 5.743

5.743

述曰：謂眼等五，亦依眼等五有色根。此第六識，若等無間，若俱有依，唯依意根；依唯意故，得意識名。五通意、色二所依故。若爾，七、八二識亦唯依意，或第八識唯依於意，第七依心，應名心識，或名意識。

The Commentary states: That is, the five consciousnesses beginning with the eye also rely on the five material faculties beginning with the eye. This sixth consciousness, whether in terms of the equal-and-immediate condition or the simultaneous support, relies exclusively on the mental faculty; because it relies exclusively on the mind, it receives the name 'mental consciousness'. The five, however, extend to both mental and material supports. If so, then the seventh and eighth consciousnesses also rely exclusively on the mind, or the eighth consciousness relies exclusively on the mind and the seventh relies on citta, so they should be called citta-consciousness or mental consciousness.