An Arhat's entry into Nirvāṇa without remainder is the reduction of the body to ashes and the extinction of wisdom, not the extinction of all thoughts.

After an arhat enters Nirvāṇa without remainder, his worldly dharmas of the three realms vanish and are seen no more. The three-realm world—including the desire realm, the form realm, and the formless realm—is called the vessel world (bhājana-loka), which contains an immense amount of material form. If an arhat enters Nirvāṇa without remainder, not only do the material forms corresponding to the seven consciousnesses—such as the subjectively imagined realm, the real-object realm, and other realms—cease to arise, the essential-object material forms corresponding to his eighth consciousness also cease to arise. Without the essential-object realm, there is no subjectively imagined realm, no dependent realm, and no real-object realm. These realms are the circumstantial-retribution worldly dharmas manifested by the karmic seeds of the three realms; the direct retribution is the five-aggregate body.

It is ordinary worldly people who become utterly disheartened and despondent; sages are without such thoughts, so there is no question of them becoming despondent. An arhat cannot become utterly disheartened the way worldly people do. The meaning of being utterly disheartened is that one has many hopes and wishes in one's mind that cannot be realized, and thus one becomes greatly disappointed, ending up with no thoughts or ideas whatsoever in the world—but the manas still has many ideas and wishes that have not ceased; they simply cannot be realized.

The Buddha used the term "extinguishing the body and obliterating wisdom" to describe the folly of the arhat. "Extinguishing the body" means extinguishing the present physical body of the five aggregates as well as the five-aggregate bodies of immeasurable kalpas in future lives—abandoning them all. "Obliterating wisdom" means obliterating the wisdom of liberation from the three realms. The meaning is that the arhat abandons both body and mind, and this is called liberation, called tranquility.

In fact, what is true liberation? It is that when facing all realms, one is as if there were no realms at all—without desire or seeking, seeing as if not seeing, hearing as if not hearing, applying the mind to nothing, neither actively engaging nor avoiding, not being influenced or stained, utterly at ease. The Buddha is precisely thus at ease and liberated: it does not prevent Him from having a five-aggregate body of liberated form, nor from having the seven consciousnesses transformed into wisdom; body and wisdom both present, accompanying each other without separation, and no heavenly māra or non-Buddhist path can do anything about it. This is the Buddha's realm of the abodeless nirvāṇa (apratiṣṭhita-nirvāṇa): He abides in no dharma whatsoever, being unconditioned like the undefiled consciousness (amala-vijñāna), unconditioned like suchness (tathatā), yet this does not hinder the conditioned—like the great mirror-like wisdom (ādarśa-jñāna), conditioned yet unconditioned, the conditioned and the unconditioned fused seamlessly into one, inseparable. This realm is incomparable; the realm of sentient beings cannot be compared with the Buddha's realm.