The fundamental experience and existential question faced by every human being is that we are mortal and we are born, live and struggle through our lives, and then we die. We strive to understand why we are alive, whether we have some purpose that goes beyond the mere process of living and dying, and how we are to live our lives in pursuit of that purpose. The sages who have delved deeply into these questions raise the concept of immortality, which represents the opposite of what we experience today. Is immortality in our future? Can it be attained? If so, what form does it take, and how do we go about achieving that status? These are the questions that the Upanishads, and in particular the Kena Upanishad, raise through the expression of their understanding of the meaning and direction of human life.
Sri Aurobindo observes: “The mortal life is a dual representation of That (n.b. the Brahman) with two conflicting elements in it, negative and positive. Its negative elements of death, suffering, incapacity, strife, division, limitation are a dark figure which conceal and serve the development of that which its positive elements cannot yet achieve, — immortality hiding itself from life in the figure of death, delight hiding itself from pleasure in the figure of suffering, infinite force hiding itself from finite effort in the figure of incapacity, fusion of love hiding itself from desire in the figure of strife, unity hiding itself from acquisition in the figure of division, infinity hiding itself from growth in the figure of limitation. The positive elements suggest what the Brahman is, but never are what the Brahman is, although their victory, the victory of the gods, is always the victory of the Brahman over its own self-negations, always the self-affirmation of His vastness against the denials of the dark and limiting figure of things. Still, it is not this vastness merely, but the absolute infinity which is Brahman itself. And therefore within this dual figure of things we cannot attain to our self, our Highest; we have to transcend in order to attain. Our pursuit of the positive elements of this existence, our worship of the gods of the mind, life, sense is only a preparatory to the real travail of the soul, and we must leave this lower Brahman and know that Higher if we are to fulfil ourselves. We pursue, for instance, our mental growth, we become mental beings full of an accomplished thought-power and thought-acquisition … in order that we may by thought of mind go beyond mind itself to the Eternal. For always the life of mind and senses is the jurisdiction of death and limitation; beyond is the immortality.”
Sri Aurobindo, The Upanishads, Kena Upanishad and analysis, pg. 102, 161-164