Indeed, it should be obvious that their belonging to different Vedas and different periods does not prevent a continuity of purpose running through them, as traditionally arranged, any more than the difference in age and provenance of the stones in a necklace prevents it from having a composite, harmonious beauty.

According to the Muktika Upanishad (and this is generally accepted by scholars), there are in all 1180 upanishads, one for each branch of the four Vedas: that is 21 for the Rig Veda, 109 for the Yajur, 1000 for the Sama and 50 for the Atharvana. Out of these, however, only 108 are listed in the Muktika as being the essence of the Upanishads. This list also is generally accepted, though not its sequence. The further division by the Muktika of these 108 into ten more important and 98 less important is also generally accepted. It has indeed been greatly strengthened by the fact that Shankara chose these ten to write commentaries on.

No Upanishad except the Muktika mentions any other by name. The Muktika, in giving a list of the 108, places itself last, and we may surmise that it was the latest written from its being able to give the list at all. Furthermore, it defines the purpose in studying the Upanishads in the words of Sri Rama to his disciple Maruti as being to escape from the miseries of earthly life and attain Mukti.

Students would be well advised to study the Muktika first as an introduction to the others and then to go through them one by one in the order there laid down. What is not explained in one is clarified in the following. True, all of them deal with Brahman and samsara in a general way, but each has a different approach. Students who confine themselves to puzzling over individual mantras in each separate Upanishad are like the traveller who can't see the wood for trees; they should also read them through as a continuous whole in the prescribed order.

The Mandukya, the 6th, is the real nucleus. The first five are meant to prepare the mind of the seeker and to build up a proper background for it. The first floor of the edifice is started with the seventh, the Taittireya, and roofed with the tenth, the Brihadaranyaka. Then the 11th to 32nd complete the second storey of the edifice. The remainder complete the entire building and the garden in which it stands.

To be more precise: the Ishavasya, the first of all, welcomes the student on his own level. It says in effect, as a loving mother might to her son, "Your troubles are of your own making. Everything in the entire universe is pervaded and controlled by the Lord (Isha). Of course you have a right to a full span of life and should try to safeguard your right, but do give up greed. Be content with what comes to you and what the Lord gives you and don't try to grab what is given to others. Grabbing only increases your troubles. Greed is at the root of them. Naturally, if you grab you will have to suffer", and so on. It then proceeds to explain how all-embracing is the power of the Lord and how we cannot escape if we transgress the rules. No other Upanishad gives this initial and essential advice.

The seeker's interest is thus awakened and in the second Upanishad, the Kena, he asks: "Who is this Lord? Is it due to Him that we breathe, think, talk and live? Do the sun, moon and stars rise and set due to Him? Is it He who makes the wind blow and the fire burn?" "Yes, of course," he is told.

While in the Isha the Lord is referred to impersonally as That (Tat), the term Brahma (That Great) is now introduced. Further, the seeker is recommended to learn the Vedas and Upanishads, these words being brought in for the first time. He is assured that if he lives light, without grasping, not only will he himself be happy but all around will esteem him (samvachhanti). It is emphasised that renunciation of greed, and knowledge of the Lord are to be achieved here and now, in this lifetime. If they are not, a great opportunity will have been lost. So the seeker is brought to ask to be taught the Upanishads.

This is followed by the Katha with its interesting story of death and what comes after, in order to impress upon the seeker that not even by death can he escape the repercussions of his misdeeds in this life. He is told that the only escape from his troubles is by seeking the Lord and behaving in a way that will please Him. To reap the fruit of right conduct, he is told, is better than possessing all the world's wealth. What is right should be chosen in preference to what is pleasing. So he should follow the injunctions of the Vedas sincerely and give his full attention to what follows.

Having dealt with the seeker as an individual, the Upanishads now digress in the Prasna to a consideration of the universe, its origin and development, emergence and dissolution. The Sage explains to his six disciples, who seem to symbolise the six seasons, how the cycle moves. Significantly, he asks them to stay in his ashram for a full year, the annual cycle. The seeker is here made aware of his place in the cosmic cycle, of his birth and development and the inevitability of his living in the world and coming to terms with his environment.

The Mundaka then follows, explaining the sole effective source of knowledge and the distinction between vidya and avidya, knowledge and ignorance. It points out the practical means of attaining the goal. In this Upanishad is explained how the boundless multiplicity of the world springs from a single basis, the universal Suvarnam or 'golden dust' which, by its endless permutations and combinations, produces the world of appearances and qualities, including life and motivation. This Upanishad cautions the seeker that it is only by the Grace of the Lord that we can hope to find Him and escape falling into materialism.

And now the Mandukya, the great sixth, which, though short, explains effectively how both the macrocosm and microcosm emerge from the single basic essence and are dissolved again into it. It shows the seeker how unreal his own worldly pleasures and pains are and how they disappear when he realizes the Infinite in himself.

Just as the thread of a single unfolding purpose has been traced briefly through the first six Upanishads read in the traditional order, so the earnest seeker will find it continuing through those that follow. Let him therefore study them as one continuous whole, remembering that the purpose of the entire sequence is to lead him "from the unreal to the Real, from darkness to Light, from death to Immortality."