大乘百法明門論開宗義決 1.73

1.73

恒審思量勝餘識者。夫言意者思量為義。唯第七識恒審思量。由此應作四句分別。若第八識恒而不審。其第六識審而不恒。若前五識非恒非審。唯第七識亦審亦恒。是故恒審勝餘識也。

Regarding 'Constantly examining and deliberating, it surpasses the remaining consciousnesses': the term 'intellect' (manas) has the meaning of deliberation. Only the seventh consciousness constantly examines and deliberates. From this, a fourfold categorization should be made: the eighth consciousness is constant but does not examine; the sixth consciousness examines but is not constant; the first five consciousnesses are neither constant nor examining; only the seventh consciousness both examines and is constant. Therefore, constantly examining and deliberating, it surpasses the remaining consciousnesses.