Commentaries on the Vedas                       
As the Vedic literature is difficult to understand, their Bhashyas or commentaries come to our aid in bringing out their inner meanings. Over the centuries there has been a galaxy of commentators on Vedas among whom Sayanacharya of the 14th century holds a unique place both in terms of the outstanding quality of his works and their sheer volume.

Upanishads
After having had an aerial view of the Vedas and the place of the Upanishads in them we may now venture to go deeper to fathom the depths of the Upanishads.
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If there is one mass of scriptures in the world that has sustained the spiritual thinking over the millennia, it is the Upanishads. All the schools of thought, religious movements that flourished in the later periods in Indian history have been a byproduct of the Upanishadic thinking. They gained respectability and acceptance only because they followed the footprints of the Upanishads.

Meaning of the word ‘Upanishad’
Several meanings of the word Upanishad have been given by the scholars. Sankara interprets this word to mean knowledge of God implying that the central theme of the Upanishads is that knowledge which destroys ignorance of man and leads him to Brahman’. This definition conveys three aspects of divine knowledge or wisdom which
1.    loosens the bond of Samsara of a being
2.    destroys his inborn ignorance (Ajnana) of his real nature and
3.    leads him to Brahman or God, the Absolute.

Etymologically the word ‘Upanishad’ means that which is taught to the pupils sitting at the feet of their teachers. Thus the Upanishads are books of wisdom taught by the accomplished teachers to the deserving students.

Actually the philosophy of the Upanishads was treated as Rahasya or Guhya or confidential not meant as a popular philosophy for an average person. The reason is the common saying that half-knowledge is dangerous meaning thereby that the highest wisdom could he misunderstood by those who are not mature enough to absorb its deeper significance.

The initial hesitation of Yama, the Lord of Death, to part with the highest knowledge to Nachiketa till he proved his worthiness illustrates this point He offered the young Nachiketa all kinds of temptations to divert his attention. But Nachiketa stood the test successfully concentrating on his goal of obtaining the secret knowledge. Ultimately, Lord Yama had to relent and began His exposition which is the subject matter of the Kathopanishad.

Since the Upanishads form the concluding portion of each of the Vedas they are often spoken of as Vedanta i.e. the end or Anta of the Vedas, The Upanishads are the primary texts of Vedanta and in the common parlance, the word Upanishad itself came to mean Vedanta Philosophy.

Number and Classification
The number of works that go by the name Upanishad and available today in print exceeds 200. The Muktikopanishad gives a list of 108 Upanishads. However, the principal Upanishads are accepted to be those which Adi Sankaracharya who lived between 788 and 820 A.D. chose to comment upon.

Sankara was the earliest commentator on the Upanishads. He chose only 10 Upanishads for his commentaries. According to some scholars he commented upon 11 Upanishads. He refers to 4 more Upanishads in his commentary on Brahma Sutra.

Considering the ones chosen by him for commenting and as reference material as the most ancient and authentic, they are termed as major or principal Upanishads. We may list them as follows

Dr. Radhakrishnan adds 4 more Upanishads to the list of Principal Upanishads viz.
•    Maitri Upanishad
•    Subaala Upanishad
•    Kaivalya Upanishad
•    Vajrasuchika Upanishad

Chronologically speaking, some scholars classify the Upanishads into three groups belonging to the three periods to which they are attributed.

The first and the oldest group Consists of 6 Upanishads headed by the Brhadaranyaka followed by the Chandogya. Both these Upanishads are written in prose and both are acknowledged as the most authoritative presentation of the central doctrines of the Upanishads. The other four in this group are the Taittiriya, Aitareya, Kaushitaki and Kena Upanishads.

The second group, mostly in verse form set to standard metres, comprises 5 Upanishads viz, the Katha, Isa, Shvetasvatara, Mundaka and Mahanarayana.
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In the third group we return to prose which consists of 3 texts viz. Prasna, Mandukya and Maitri or Maitrayani Upanishads.

Most of the Upanishads outside the above list belong to a later era of Indian culture, written mainly to propagate specific cults or sects; Even then, they made a considerable contribution to the religion and ethics of the times and developed Vedantic spirit among the people. They are called minor Upanishads and grouped together in 6 categories Viz.

The Vedanta Upanishads follow the lines of major Upanishads in their principles. Siva, Sakta and Vaishnava Upanishads propagate the cults of Siva, Sakti and Vishnu respectively. The Yoga Upanishads deal with Hatha Yoga and Raja Yoga based on Patanjali’s Yoga Sutra and other works. Sanyasa Upanishads deal exclusively with Monasticism, its ideals, practices, rules and regulations.

Spread of Upanishads to other countries  
Another important fact in this connection is about the spread of Upanishads to the rest of the world particularly to the West. A collection of 50 Upanishads was translated from Sanskrit to Persian in the year 1656 under the name of Oupnek’hat at the instance of Sultan Mohammed Dara Shukoh son of the Moghal King, Shahjehan.
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This Persian work was later translated into Latin in 1801-1802. Thereafter, German scholars translated the Latin version into German from where it was taken to the shores of England by others like Bohtlingk and Deussen. Max Muller, who lived between 1823 and 1900 AD, selected 12 major Upanishcids in his Sacred Books of the East Series which were published in two volumes in 1879 and 1884

Paul Deussen, another German scholar wrote two masterpieces on the Upanishads in German which were translated into English later. His works are entitled ‘The Philosophy of the Upanishads’ translated into English by Rev. AS. Geden and ‘Sixty Upanishads of the Veda’ in two volumes translated into English by Professors V.M. Bedekar and G.B. Palsule of Pune.

The well noted work by an Englishman is ‘The Thirteen Principal Upanishads’ by Robert Earnest Hume.

Commentaries on the Upanishads
By its very definition Upanishads are works of deep thoughts requiring special efforts and skill to understand. The language used is archaic dating back thousands of years. Because of their affiliation with sacrificial and ritualistic religion, their concepts are not easily intelligible to us, removed as we are, by millennia from those ideas. Hence it is impossible for any one to understand them much less get consistent understanding of them without an authoritative .commentary.

Sankara was the earliest and the first to comment upon the Upanishads. It goes to the eternal credit of Sankara that through his masterly commentaries he brought out the Upanishads from obscurity and made them accessible and intelligible to a wider audience. His followers wrote explanatory works on Sankara’s commentaries which became the source books of Hindu philosophy.

Ramanuja who lived between 1017 and 1137 AD, did not comment on any of the Upanishads but had enriched some of their concepts in his Vedantasangraha. His follower Rangaramanuja completed the task by commenting on all the major Upanishads.

Madhvacharya who lived between 1197 and 1276 AD wrote brief commentaries on all the ten ancient Upanishads upon which his followers had also written explanatory studies.

Among the Upanishads, Isavasyopanishad attracted the attention of the maximum number of scholars and sages who had commented upon it over the centuries.

Present Position
The audience to the Upanishads is ever growing aided by the contributions of subsequent commentators, thinkers and sages. In the present age Swamijis like Vivekananda, Aurobindo, Sivananda, Chinmayananda and Dayananda did yeoman service for spreading the knowledge of Upanishads across the globe particularly in the U.S.A. Nowadays, thanks to the modern science of information technology the whole world has become a receptive audience to the knowledge of Vedanta disseminated through the Internet.
Glory to the Vedas! Glory to the Upanishads! Harih Om!