साधकं ज्ञानभक्तिभ्यामुभयं तदसाधकम् ॥ १२ ॥
lokaṁ nirayiṇas tathā
svargiṇaḥ — the residents of the heavenly planets; api — even; etam — this; icchanti — desire; lokam — earth planet; nirayiṇaḥ — the residents of hell; tathā — in the same way; sādhakam — leading to achievement; jñāna-bhaktibhyām — of transcendental knowledge and love of Godhead; ubhayam — both (heaven and hell); tat — for that perfection; asādhakam — not useful.
The residents of both heaven and hell desire human birth on the earth planet because human life facilitates the achievement of transcendental knowledge and love of Godhead, whereas neither heavenly nor hellish bodies efficiently provide such opportunities.
Śrīla Jīva Gosvāmī points out that in material heaven one becomes absorbed in extraordinary sense gratification and in hell one is absorbed in suffering. In both cases there is little impetus to acquire transcendental knowledge or pure love of Godhead. Excessive suffering or excessive enjoyment are thus impediments to spiritual advancement.