大毘盧遮那經阿闍梨真實智品中阿闍梨住阿字觀門 1.16

1.16

Furthermore, this method of distributing syllables is the three-tiered secret maṇḍala of the Great Compassion Garbhakośa. Unless one is a person who has gathered the practice of true Vidyā and is fit to receive transmission, only then may it be transmitted through mental intention; it cannot be recorded in writing, and so masters have transmitted it orally (the sūtra merely refers to it as the 'Chapter on the Wheel of Syllables'). The twelve syllables from *I*, *Ī* to *O*, *AU* are all dispersed outside the syllable wheel as