首楞嚴義疏注經 9.60

9.60

This fourth dhyāna is free from the eight calamities and excels the lower grounds, so it is called the Unshakable Ground. However, it has a count of kalpas, and when lifespan ends it must be abandoned; hence it is said to be 'not the true unshakable.' The *Kośa* says, 'Yet that vessel is not permanent, because conscious beings alike arise and cease.' Ordinary beings cultivate concentration and relish birth, which is called 'having attainment.' When concentration and wisdom are balanced and equal, able to abandon suffering and bliss, excelling all the lower heavens, it is called 'effort brought to full maturity.'