When the mind, held in check by the practice of yoga, comes to rest, and when, seeing the self by the self, one is content in the self…
Explanation
Krishna is still describing to Arjuna the person who has mastered yoga, following the image of a lamp that does not flicker in a windless place. Here the mind (citta), restrained by steady practice, settles into stillness, and the yogi finds contentment in the self (ātman) without needing anything outside. Advaita readings take "the self seeing the self" as the Self recognizing its own nature, while devotional (Vaishnava) readings often take it as the individual self perceiving the Supreme within. The sentence continues into the next verse.