首楞嚴義疏注經 9.2

9.2

Second, the form realm (rūpadhātu): it is named after what is superior because within this realm the material forms of both circumstantial and direct retributions are exquisite. It is collectively called the Brahmā worlds because *brahmā* means pure—being free from defilement of desire, produced by dhyāna, and distinct from distraction and disturbance. This realm contains eighteen heavens in all. According to the *Kośa*, which states: "The [first] three dhyānas have three each, and the fourth dhyāna has eight," the Heaven of Non-conception (Asaṃjñisattva) is excluded. Relying on the Mahāsāṃghika school, in agreement with the present sūtra, the Heaven of Non-conception is added.