Pada Sphota is that from which the meaning of a word when uttered breaks forth. Sphota is a contribution of Sanskrit Grammarians. They believe that there is a unitary factor latent in every word, which is evoked when the letters and syllables are successively uttered or heard. The upholders of the theory recognize one ultimate sphota, which is infinite, eternal, and self-existent. “Each particular sphota latent in the word or a sentence is but an apparent variation of the universal, immutable sphota. So sphota is essentially one and is identical with Brahman.” (Swami Satprakashananda). In other words, the imperishable Brahman is the underlying essence of the letters, words, sentences and their meanings (sabda tattva).
Bhartrhari, a grammarian of the 5th century CE, in his famous work Vakyapadiya, has said that sphota is the essential akshara brahman, a form of Brahman due to which we become aware of the universe. It is called sabda tattva, which is the first manifestation of Brahman in the form of the universe. Sounds (dhvani or nada) are necessary to make it explicit. But, before being made explicit, sphota exists in the pre-verbal potential state as a unity of word, meaning, thought and idea. It is called the pasyanti stage of language. It is an invariant, sequenceless and partless whole.
Patanjali, in his Mahabhashya, has defined sphota as a unit of sound having a succession of sound units. Bhartrhari has classified sphota into three categories, namely, varna sphota (consisting of letters or varnas), pada sphota (made up of words, which are sequences of varnas) and vakya sphota (whole sentences containing words or padas in a particular order).
The origin of the doctrine of sphota is not known. An early grammarian called Sphotayana is believed by some to be its founder. His name has appeared in Panini’s Ashtadhyayi in rule VI.1.123. (5th century BCE).
Out of the three varieties of sphota, Bhartrhari considered the vakya sphota as the most important.
The Mimamsakas take the varna to be eternal. The Naiyayikas argue that each varna and word leaves its trace behind when heard and the last word, mixed up with all traces, produces meaning. Both Mimamsakas and Naiyayikas are opposed to sphota theory.