In Bhartrhari, we find the only exception who delves into explaining nature of mantra-s. He formalizes the Mantrabhaga through his unique theory of aksara-brahman or Sabdadvaita without violating the cardinal form of ekavakyata in tune with the traditionalists view. He spells this ‘linguistic contiguity’ through statements like ‘anadi-nidhanam brahma sabdadvaitam yadaksaram’ etc. The concept of aksara unfolded in Paniniya-Varttika and Mahabhasya is also found to be very much relevant in the context of Bhartrhari’s Sabdadvaitavada.
In the Brahmakanda of Vakyapadiya, he illustrates the algorithm of mantras lying in eternity as Para Vak, revealed to the Rsi-s through Yogaja pratyaksa or supersensory perception. At the pasyanti level their experience consumed (sphutya/sphota-bhava; while at the madhyama level these were stuffed in forms as grahya/grahaka which was considered to be transformation or parinama of Para Vak. These cognitive forms, while articulated through physical verbal organ, gained the status of vaikhari. The word ‘Veda’ itself reveals the truth as stated. The empirical world, both internal and external, are wrapped up in this form and remain to be identical with sabda, although referred to as padartha or artha in terms of their jnana-visayata and vyavahara-visayata. Asara-Brahma in assistance with Kalashakti presents them as real entities though padarthas are nothing but vivarta, illusory perception of shell-silver or rope-snake.