大毘盧遮那成佛經疏 7.7

7.7

The sūtra says: 'Secret Lord! What is the mantra teaching?' This means that the syllable A gateway and so forth are the phenomenal characteristics of the mantra teaching. Although the characteristics are not different from the essence, and the essence is not different from the characteristics, the characteristics are not fabricated, and having been accomplished through cultivation, they cannot be shown to others; yet, without departing from liberation, they manifest as sounds and syllables, each sound and syllable being a gateway to enter the dharmadhātu; hence it is called the mantra teaching. Ultimately speaking, the mantra teaching should pervade all names and words across all regions and destinies. It is only because the traces of the Tathāgata's appearance in the world began in India that those who transmitted the Dharma have provisionally clarified its meaning in terms of Sanskrit.