The Subtle and Refined Delusive Thinking of the Aggregate of Consciousness in Volume Ten of the Śūraṅgama Sūtra

This means that the aggregate of formations is a hidden and secret delusion, difficult to perceive. "Hidden" means dark and secret; "concealed" means hidden away—both refer to the phenomena of arising, ceasing, and change in the physical body that are not easily noticed by people. These phenomena are not something the subjective conscious mind can control; rather, due to the power of karma, the body undergoes various changes as time flows on. If the power of karma were to disappear, one would enjoy eternal youth without aging, as in the case of the beings in the land of bliss (Sukhāvatī) and the devas of the desire realm and the form realm.

The hidden and concealed delusion is also a delusion; the aggregate of formations, which is not easily perceived, is likewise a product of delusion, flowing on and on without abiding from thought to thought—prior thoughts arising and subsequent thoughts ceasing—like subtle waves secretly flowing, with birth, aging, sickness, and death never ceasing even for a moment. If delusion is extinguished, the aggregate of formations will not arise; then there is the tranquility of nirvāṇa, with permanence, bliss, self, and purity.