Realm, and Persons Beyond the Ordinary Threefold Scheme

T1606 defines each of the three plainly: the ordinary being is one who, born and raised within a given realm, has not yet attained any of the noble teachings at all. The trainee is one who, born and raised within that same realm, has already attained the noble teachings but still retains some remaining fetter yet to be severed. And the one beyond training is one who, born and raised within that same realm, has already attained the noble teachings and retains no remaining fetter whatsoever. This same threefold pattern — ordinary being, trainee, one beyond training — repeats identically across all four realms of rebirth, the desire realm together with each level of the form and formless realms, giving a total of twelve distinct combinations of person and realm.

T1606 explains why the bodhisattva of the desire and form realms deserves its own separate classification: such a bodhisattva has, in fact, already mastered the very meditative absorption that would allow rebirth in the formless realm, and could take such rebirth if desired, yet deliberately declines it and remains within the desire or form realm instead. The reason is entirely practical — a bodhisattva of genuine, superior spiritual power takes rebirth wherever it can actually benefit and bring happiness to sentient beings, and the formless realm, lacking any physical form through which such beings could be reached and matured, is simply not a place where that work can be carried out. Skillfully turning back from the formless realm's own deeper absorption while still not losing the meditative happiness already attained, such a bodhisattva instead takes rebirth in whichever of the two lower realms will actually serve the beings still to be matured.

The pratyekabuddha of the desire realm stands apart from the śrāvaka-vehicle and Mahāyāna persons already classified earlier in this same chapter because this particular vehicle's own defining feature — awakening spontaneously, without a living teacher, in an age when no buddha has yet appeared — locates it specifically within the desire realm rather than distributing it, as the other vehicles are, across all three realms alike.

And the inconceivable Tathāgata is named this way precisely because a single, complete account of the buddha's own activity cannot be confined to any one of the ordinary categories already given. T1606 specifies what the full span of this manifestation actually includes: everything a bodhisattva does, from dwelling in the Tuṣita heaven's own palace all the way through to manifesting the great miraculous display that subdues Māra's own army, together with everything a buddha then does, from manifesting complete and perfect awakening all the way through to manifesting great final nirvāṇa itself — the entire arc of a buddha's career, taken as a single, unified person that the ordinary categories of ordinary being, trainee, and one beyond training were never designed to capture in the first place.