Taittiriya Upanishad deals the three stages of spiritual development of one aspiring the supreme Lord, from the gross to the subtle, from the subtle to the spiritualwhich are discussed and enumerated in the three sections - Shikshavalli, Brhmanadavalli and Bhriguvalli.
The first section Shikshavalli, deals with instruction regarding the rules of pronunciation, with emphasis on recitation of every word, every syllable with immaculate intonation and accent with scrupulous accuracy and efficacy, for scrupulous accuracy on the spiritual Path depends on moral and ethical base and sincere austerity and perfected penance. A legend recorded in Braahmanas points out that Twashtri performed a sacrifice to produce an avenger of his son by Indra, produced owing to an error of accentuation, not a slayer of Indra, but one of whom Indra became the slayer.