How do you know? Ūrdhvaṁ gacchanti sattva-sthāḥ (BG 14.18). If you act just like a qualified brāhmaṇa, sattva-sthā, sattva-sthā means brāhmaṇa—then you get your promotion in the higher planetary system ūrdhvam. Ūrdhvaṁ gacchanti sattva-sthāḥ. If you act like a brāhmaṇa, then get your promotion to the higher planetary system, Janaloka, Maharloka, Tapoloka, Brahmaloka, Siddhaloka. There are so many planets. The people do not know. There is no such education. But we have got this knowledge from the Vedic literature. Ūrdhvaṁ gacchanti sattva-sthā madhye tiṣṭhanti rājasāḥ (BG 14.18). If you have got the qualification of rajo-guṇa, creative energy, then you remain in the middle planetary system, Bhūr, Bhuvaḥ, Svaḥ. Those who are brāhmaṇas know gāyatrī-mantra, oṁ bhūr bhuvaḥ svaḥ.
Sattva-stha means
Lectures
Bhagavad-gita As It Is Lectures
If you act just like a qualified brāhmaṇa, sattva-sthā, sattva-sthā means brāhmaṇa—then you get your promotion in the higher planetary system ūrdhvam.
Lecture on BG 4.17 -- Bombay, April 6, 1974: