大方廣圓覺修多羅了義經略疏 2.636

2.636

The latter seven wheels each mark quiescence as primary and then combine the remaining two. This first is the contemplation of the empty ocean of precious radiance. The Śūraṅgama Sūtra says: 'Together entering the Tathāgata's empty ocean of precious radiance.' Here the contemplation of the luminous mind is the brilliance of original enlightenment, like the precious radiance; the subsequent stillness contemplation is like the empty ocean.