There are a few points in the teachings of Buddha which have always been points of controversy, wherein great interpreters have differed from one another. The most important of these are two: first, the well-known Anatta doctrine, the teaching that there is no permanent soul; this teaching is so pervasive of Buddhism that we can take it as part and parcel of the original Buddhism. In the second discourse delivered by Buddha at the very beginning of his public ministration at Sarnath, entitled the Anattalakkhana Sutta, we have an exposition of this Anatta doctrine; so that it is necessary for us to understand what Buddha meant by this Anatta or Ananta doctrine, which apparently represents a fundamental point of departure from the great teachings of the Upanishads on the subject of the true nature of the ultimate reality.
When man attains nirvana, what does he realize and what happens to him? Does he attain something positive or something negative? On this subject the language of the Upanishads is clear, in spite of all the prefaces with which they have expounded it, stating that the ultimate Truth is that from which speech and thought recoil, that it transcends all specifications. In spite of this kind of reservation, the Upanishads leave us in no doubt that the ultimate Truth is a Yes and not a No. It is a positive something and not a negative nothing; the Upanishads speak of it as Brahman, the One without a Second, the Self of all, beyond sense and thought, the Impersonal, the Transcendent as well as the Immanent. Even though it transcends specifications by speech and thought, yet it is a positive reality. The Katha Upanishad (II. 3. 12-13) says:
‘This Self cannot be reached through the organs of speech or thought or sight. How can It be realized except through one who says “It is”. It must be comprehended as “is” (and not as “is not”).
The last category of thought can only be a position and not a negation according to the Upanishadic thought. On this basis when we proceed, we do not see in the teachings of Buddha any clear reference to the reality of a changeless Being behind the fluctuations of Becoming.
As in the case of the soul, it is something composite, impermanent and ultimately insubstantial, so in the case of the world, it is also impermanent and insubstantial; but with regard to the ultimate Reality realized in nirvana, Buddha did not say that it also is impermanent and insubstantial. He did not say anything about it at all. He was silent about it, as he was also silent about the nature of the individual in the state of nirvana and evaded giving direct answers to questions relating to them. That is a point which we shall have to discuss, the meaning of this silence of his on the subject of the ultimate Reality in man and in the universe, and to determine his position in the great philosophical tradition of the Upanishads.
In the life of Buddha we can trace three eventful periods. The first is the period of his youth and early manhood when as Siddhartha Gautama, he lived a life in the world, all the while yearning to gain the truth of all life and existence. Gifted as he was with a keen mind, a pure mind that questions and struggles to find the truth, the spirit of utter dispassion for a life of empty pleasures came upon him at the age of 29, and he entered the second stage of his career, renunciation and whole-soul search after Truth. Gautama getting the spirit of dispassion and leaving the world of evanescent pleasures in search of Truth is not a new or strange phenomenon in Indian history. Hundreds and thousands of ordinary and gifted men and women had passed through the same experience. They had followed the path of renunciation to search for the meaning of life, so that at the time of Gautama there were so many wandering teachers who were also inspired by the great desire to penetrate the world of appearance and come in touch with Reality.
This tendency to go forth into the homeless state in search of Truth was well established in the age of the Aranyakas and the Upanishads; they give us arresting pictures of gifted men and women imbued with the spirit of renunciation and earnestness, with hearts pure and tranquil, leading lives of meditation and truth-seeking, alone or in groups, in forests and quiet retreats.
--- Excerpt from Dynamic Spirituality for A Globalized World, A commemorative volume of selections from the works of Swami Ranganathananda, late president of RK Math & Mission