大乘義章 13.3

13.3

八禪定義四門分別（一通解八禪　二別釋八禪　三明定具　四明定難）

The doctrine of the eight dhyānas and samādhis is differentiated through four gates: (1) general explanation of the eight dhyānas; (2) distinct explanation of the eight dhyānas; (3) clarifying the requisites of samādhi; (4) clarifying the difficulties in samādhi.