阿吽

(sa) ahūṃ, the supposed foundation of all sounds and writing, '(sa) a' being the open and '(sa) hūṃ' the closed sound. '(sa) A' is the seed of Vairocana, '(sa) hūṃ' that of Vajrasattva, and both have other indications. '(sa) A' represents the absolute, '(sa) hūṃ' the particular, or phenomenal.