大方廣圓覺修多羅了義經略疏 2.1344

2.1344

非器不聞名祕，隨器異聞名密。三昧之名其數無量，圓覺三昧是彼根源，故稱王也。

Not being heard by those who are not fit vessels is called "secret"; being heard differently according to the vessel is called "hidden." The names of samādhis are boundless in number; the samādhi of perfect enlightenment is their root and source, hence it is called the "king."