瑜伽論記 4.63

4.63

增上心者，定體名心，即由定體清淨故能慮，亦可由同時心王有清淨，令彼定數正審思慮。

Regarding 'higher mind': the essence of absorption is called mind. Thus, because the essence of absorption is pure, it can deliberate; alternatively, because the simultaneous mental king is pure, it causes that factor of absorption to correctly examine and deliberate.