奥义书——吠陀传统的哲学核心，阐明梵、真我、知识、行动与解脱的本质。十部主要奥义书，另加精选的毗湿奴派小奥义书。
On the inner sound: the syllable Oṃ is described as a bird, and then come the ten sounds heard by one who is concentrated, and how the mind clings to the last of them as a bee to honey.