By knowing the self-shining One, all the limitations of ignorance end forever. With the cessation of all sufferings, there is release from birth and death.
Shvetashvatara Upanishad

We associate the Upanishads with the spirituality of ancient India, yet they remain sources of guidance and insight for anyone in quest of spiritual light. This is because their message transcends time and place and the boundaries of any particular religion. They appeal not to man's need to believe, but to his urge to know—the power of enquiry present in every human mind. And they open a way to a deeper understanding, so that we do finally know what we came into the world to know: the ultimate Truth about the nature of experience. We know this through knowing the nature of our own true Self.

The living heart of the Upanishads is therefore not different from the heart that beats within our own breast. The Upanishads teach us about ourselves, as spiritual beings. The word 'heart' is used as a metaphor and a pointer to the subtle, inmost essence of our own being, in other words, our true Self. It is that place of inner retreat, which will, when opened up, reveal that the spiritual light and power is within and without, and that it is our real nature.

In one of his writings the Indian philosopher Shri Shankara tells the story of a little boy, a prince, who was one day discarded by his parents, and placed in the hands of foster parents who were very poor and used to catch birds in order to make a living. It was not long before the boy felt he belonged to them, and was one of them, and forgot completely his royal nature, and followed the duties and profession of a bird-catcher.

Some time later, a court official happened to be journeying through the area, and recognized the boy as the king's son. He took him aside for a talk, gently reminded him of some of the details of his early environments, and said: 'You do not belong here. Give up this false idea that you are a fowler. You are heir to the throne of this whole kingdom. You are a prince. Be what you are, and come back with me to your true home.'

Shri Shankara tells this story in order to shed light on the inner meaning of a particular verse from the Brihadaranyaka Upanishad:

As a spider moves along the thread which it produces out of itself, and as from a fire tiny sparks fly in all directions, so from the [supreme] Self emanate all organs, all worlds, all gods and all beings. Its secret name is the Truth of truth. The vital force (the life principle) is truth, and It is the Truth of that. (II.i.20)

The teaching is that man, in his true nature, his true Self, is ever at one with the divine, just as sparks are one with the fire. The Divine is, as it were, the great Self of all—the Self of the entire universe. It has produced the multiplicity of creatures as a kind of illusory projection or emanation from itself. Therefore we are not really separate from the Divine, and never have been. But like the prince, we have forgotten our true nature, and need to be awakened to it. When this happens, all error falls away, and we know that the spiritual centre of our being is one with the supreme.

This spiritual information is designed to revive our knowledge of our true nature. It is the main message and purpose of the Upanishads. Their value is to awaken us to our fundamental nature as divine peace and infinite wisdom, and liberate us from the sense that we are anything other than the Absolute Reality, which is the basis of the world of appearances and of our individual being. It is to arouse in us the knowledge: 'My Self is the Self of all.' Grief and ignorance are cancelled forever. In the words of the Isha Upanishad:

When to the man of realization all beings become the very Self, then what delusion and what sorrow can there be for that seer of oneness?

This Upanishad uses the term oneness, or unity (ekatvam) to indicate the awakened understanding. But something deeper than unity is meant, for unity is usually unity of different things, which still remain different things, though bonded together. The realization taught in the Upanishads involves awakening to one's identity with the Self of all as the only reality. So to indicate this depth and purity of understanding, another term is used: non-duality, Advaita. Advaita, non-duality, replaces all differences, including differences between things, between me and what I see, between me and God, and so on.