大毘盧遮那經阿闍梨真實智品中阿闍梨住阿字觀門 1.21

1.21

When the ācārya engages in recitation, he may contemplate the sentence wheel (padacakra). As for the sentence wheel: one contemplates the heart of the deity having a round radiance in which the letters of the mantra are arranged, turning like a wheel and joined end to end, clearly manifesting before oneself. One contemplates this wheel of letters as being like white milk, pouring continuously into the practitioner's mouth or flowing into his crown, uninterruptedly filling his whole body. Within that round radiance is the seed syllable (bīja), which is always distinct, like water flowing without end. When he is thoroughly exhausted from reciting in this manner, he merely abides in the quieted mind of the letter A.