Upanishads attempt to express the inexpressible, paint the formless, sing the glory of the voiceless beauty and the bliss of the Absolute. The purpose of the Upanishad is to engage the mind in thoughts of something which is nobler compared to something which is grosser. The Taittiriya Upanishad is a part of the Yajur Veda and it occupies a very special place within the Hindu philosophy. This particular Upanishad gives important insight into the lofty ideologies of the Hindu Philosophy. The importance of the Taittiriya Upanishad can be gauged from the fact that Sri Sankaracharya had made his first commentary on this particular Upanishad and at the same time he had quoted this Upanishad 147 times in his Bhasyas or in the Brahma Sutras. The Taittiriya Upanishad stands as a unique piece because it has explained the Subjective Reality within the seeker both in direct as well as indirect terms. The description of the Five Sheaths has been included in this particular Upanishad for the first time that is it has explained individuals as composed of five selves. It can well be claimed that it is only Taittiriya Upanishad which includes an exhaustive study of human personality.

The Taittiriya Upanishad is a part of the Krishna Yajur Veda and forms a part of the seventh, eighth and ninth chapters of the Taittiriya Aranyaka. An interesting legend is closely associated with the Taittiriya Upanishad. The legend goes that once saint Vaisampayana got angry with one of his prominent disciple called Yajhavalkya. As the guru had got angry with his disciple he demanded that his disciple should give back all the knowledge which he has acquired from the guru. Being ordered in such a manner from the guru, Yajhavalkya vomited the entire knowledge which he had imbibed from the guru. On such an occasion the guru on the other hand asked his other disciples to take the form of partridges (Taittiriya bird) and consume the leavings. It can be said that for this particular reason this Upanishad has been called the Taittiriya Upanishad.

This version of the story may sound repulsive but some scholars have given a completely different version of the story. They have said that Yajhavalkya was such a genius that he was not only able to produce the teachings of the Guru but had also added his originality and insight into the knowledge acquired. Witnessing such a situation the guru was so charmed that he had asked his other disciples to acquire the knowledge produced by Yajhavalkya as much as they could. In this regard it may be mentioned that the Taittiri-birds or the partridges are small in size but they are very active and careful and the aim of the story was to instill into the students the spirit of the small birds so that the disciples are as careful as the Taittri birds while acquiring knowledge.

It can be said that the Taittiriya Upanishad has encompassed a philosophy which is very world affirming because it has described each level of human self in a very positive manner.

There are three main sections of the Taittiriya Upanishad. They are namely the Siksha Valli (the first chapter), Brahmananda Valli (the second chapter) and the Bhrigu Valli (the third chapter). Each of the Vallis has further been subdivided into smaller sections known as the anuvakas or verses.

The first chapter or the Siksha Valli is associated with the discipline of Siksha which mainly includes the study of phonetics and pronunciation. Within the Siksha Valli there are twelve other verses or anuvakas dealing with different mantras. Each of the twelve verses deal with different types of meditation and ethical rules which a seeker of knowledge should follow in order to make his mind pure.

The central theme of the Brahmananda Valli is that one who knows the Brahman has attained the supreme knowledge. The second chapter of the Taittiriya Upanishad has further been subdivided into nine anuvakas. All the nine verses of the second chapter of the Taittiriya Upanishad have extensively talked about the different states of human beings. It has said that only the true knowledge of the Supreme Being can bring an end to all miseries and can emancipate a soul from the shackles of transmigratory existence.

The Bhrigu Valli explains how the son of the Water God Varuna known by the name Bhrigu had received the realisation of Brahman through the process of meditation under the guidance of his father. It can also be said that this Valli guides a disciple with the help of a teacher who encourages him to realise all the five sheaths so that any one of them may turn out as Brahman or God. The remaining part of this Valli has glorified the essence of food. It has said that as food is the life support so it is never desirable to insult food.

One third of the entire Taittiriya Upanishad has been dedicated to Upasanas in different forms. It can be said that the Upasanas have been included in this particular Upanishad in order to show how important is the process of self integration for a seeker of knowledge.

All Upanishads start with a peace invocation to the cosmic power so that all evils are warded off from the path of knowledge acquiring. Similarly the peace invocation in the Taittiriya Upanishad also begins with a peace invocation. The peace invocation of the Taittiriya Upanishad is:

`Om Sam no mitrah sam varunah, sam no bavat-varyama, sam na indro brhaspatih, sam no visnur-urukramah, namo brahmane, namaste vayo, tvameva pratyakasam brahmasi, tvameva pratyaksam brahma vadisyami, rtam vadisyami, satyam vadismayi tanmam-avatu, tad-vaktaram-avatu, avatu mam, avatu vaktaram. Om Santih Santih Santih.`

The meaning of this peace invocation which may be considered as the foreword of the Taittiriya Upanishad is:

`Let Mitra be propitious to us. Let Varuna bless us. Let the blessings of Aryama be with us. Let the grace of Indra and Brhaspati be upon us. Let Visnu, the All-pervading (wide-striding) be encouraging to us. Salutations to Brahman. Salutations to Thee. O Vayu! Thou are the visible Brahman. Thee alone shall I consider as the visible Brahman. I shall declare: Thou art the `Right`; Thou art the `Good.` May it protect me; May it protect the speaker. Please protect me. Please protect the speaker. Om Peace! Peace! Peace!`

Hence it can be concluded that the Taittiriya Upanishad tries to find out the true nature of God by realising all the states experienced by individuals. This Upanishad tries to focus that only knowledge of the Supreme Being can lead an individual towards the path of knowledge and righteousness.