Verse
अग्निर्ज्योतिरहः शुक्लः षण्मासा उत्तरायणम् ।तत्र प्रयाता गच्छन्ति ब्रह्म ब्रह्मविदो जनाः ॥
agnirjyotirahaḥ śuklaḥ ṣaṇmāsā uttarāyaṇamtatra prayātā gacchanti brahma brahmavido janāḥ
Fire and light and smoke or mist, the day and the night, the bright fortnight of the lunar month and the dark, the northern solstice and the southern, these are the opposites. By the first in each pair the knowers of the Brahman go to the Brahman; but by the second the Yogin reaches the “lunar light” and returns subsequently to human birth.
Gītā 8·24