大毘盧遮那成佛經疏 17.35

17.35

Next is distributing [syllables] on the body's parts. Between the eyebrows, one should place the syllable hūṃ; this is the place held by all vajradharas. Next, about four inches above the heart, visualize and place the syllable sa; this is the dwelling place of all in the Lotus-in-Hand (Padmapāṇi) division. 'My mind abides pervasively sovereign in all; I pervade various sentient and non-sentient beings, with the syllable A as the foremost life.' This means taking the syllable A as the heart, and thus pervading all with mastery and accomplishing it. This means the syllable A is not different from me, and I am not different from the syllable A. It pervades all sentient and non-sentient phenomena, and these phenomena take the syllable A as their foremost life. Just as a human has inhalation and exhalation, taking this as life, and when breathing ceases life does not continue, so too is this syllable A: all phenomena and sentient beings take this as life.