Text 171
Attaining the Supreme Court is a process that is a process of a process of a process.
427
But one who attains to My abode, O son of Kuntī, never takes birth again.
पारंपरिक परिचय
All kinds of  yogīs — karma ,  jñāna ,  haṭha , etc.—eventually have to attain devotional perfection in  bhakti-yoga , or Kṛṣṇa consciousness, before they can go to Kṛṣṇa’s transcendental abode and never return. Those who attain the highest material planets or the planets of the demigods are again subjected to repeated birth and death. As persons on earth are elevated to higher planets, people in higher planets such as Brahmaloka, Candraloka and Indraloka fall down to earth. The practice of sacrifice called  pañcāgnividyā , recommended in the  Kaṭha Upaniṣad , enables one to achieve Brahmaloka, but if, in Brahmaloka, one does not cultivate Kṛṣṇa consciousness, then he must return to earth. Those who progress in Kṛṣṇa consciousness in the higher planets are gradually elevated to higher and higher planets and at the time of universal devastation are transferred to the eternal spiritual kingdom. When there is devastation of this material universe, Brahmā and his devotees, who are constantly engaged in Kṛṣṇa consciousness, are all transferred to the spiritual universe and to specific spiritual planets according to their desires.
TEXT 17
सहस्रयुगपर्यन्तमहर्यद्रक्षणो विदुः । रात्रिं युगसहस्रान्तां तेऽहोरात्रविदो जनाः ॥१७॥
sahasra-yuga-paryantam   ahar yad brahmano viduḥ   rātriṁ yuga-sahasrāntāṁ   te’ho-rātra-vido janāḥ
sahasra —thousand;  yuga —millenniums;  prayantam —including;  ahaḥ —day;  yat —that;  brahmaṇaḥ —of Brahmā;  viduḥ —know it;  rātrim —night;  yuga —millenniums;  sahasra-antām —similarly, at the end of one thousand;  te —that;  ahaḥ-rātra —day and night;  vidaḥ —understand;  janāḥ —people.
TRANSLATION
By human calculation, a thousand ages taken together is the duration of Brahmā's one day. And such also is the duration of his night.