Praśna Upaniṣad · 5..2

एतद्वै सत्यकाम परं चापरं च ब्रह्म यदोङ्कारस्तस्माद्विद्वानेतनैवायतनेनैकतरमन्वेति

etadvai satyakāma paraṃ cāparaṃ ca brahma yadoṅkāraḥ tasmādvidvānetenaivāyatanenaikataramanveti

This, O Satyakāma, is the Supreme Brahman and also the other Brahman, the Oṅkāra. Therefore, the wise one, with this same support, attains one or the other.

Oṅkāra contains two aspects of Brahman:

  • Paraṃ Brahman — the Supreme Brahman, transcendent, without attributes (nirguṇa)
  • Aparaṃ Brahman — the “other” Brahman, with attributes (saguṇa), the cosmic Brahman

According to the level of understanding and meditation, the practitioner attains one or the other. The vidvān (wise one) uses Oṅkāra as āyatana (support, base) for his practice.

Meditation on Om is a complete path:

  • If performed with saguṇa-bhāvanā (contemplation with attributes), it leads to celestial worlds
  • If performed with nirguṇa-bhāvanā (contemplation without attributes), it leads to liberation

For the yogī, this means that Om is the vehicle, but the destination depends on how it is used. As a car can go to different places depending on the driver, so Om can lead to different states according to the meditator’s understanding.