Shurangama Sutra Volume X: The Subtle Obscurities and Delusions of the Volitional Aggregates

Original Text: Transformation never ceases, shifting subtly and incessantly. Nails grow, hair sprouts, vital energy wanes, and the countenance wrinkles. Day and night alternate in succession, yet there has never been any realization. Ānanda, if this is not you, why does your body change? If this is truly you, why are you unaware? Thus, your ceaselessly flowing formations, thought-moment after thought-moment, are called the obscure and hidden fourth kind of delusion.

Explanation: The transformations of the body never cease, shifting subtly and incessantly moment by moment. For instance, nails grow, hair sprouts, blood and vital energy diminish, the countenance wrinkles—the body's various functions renew and replace themselves day and night, yet one remains utterly unaware. Ānanda, if these formations aggregate (saṃskāra) is not you, why does your body change? If these formations are truly you, why are you unenlightened and unaware of them? Therefore, all your ceaselessly flowing formations, thought-moment after thought-moment without pause, are called the obscure and hidden fourth kind of delusion.

This explains that the formations aggregate is an obscure and hidden delusion, difficult to perceive. "Obscure" means secret and hidden, and "hidden" means concealed, both referring to the phenomena of the physical body's arising, ceasing, and transformation, which are not easily noticed by people. These phenomena are not subject to control by the conscious mind; they arise due to the force of karma, manifesting as various changes in the body over the flow of time. If the force of karma ceases, one would attain eternal youth and agelessness, like the beings in the Land of Ultimate Bliss or the celestial beings in the realms of desire and form.

The obscure and hidden delusion is still a delusion. The formations aggregate, difficult to perceive, is also a product of delusion. Thoughts flow and change without cease; a preceding thought arises and a subsequent thought ceases, like subtle waves flowing secretly, with birth, aging, sickness, and death occurring without interruption. If delusion is extinguished, the formations aggregate ceases to arise, leading to the quiescence of nirvana, characterized by eternity, bliss, true self, and purity.