I, verily, am Brahman, the One without a second, which, like the sky, is beginningless and endless, in which the whole universe...appears to be a mere shadow.—Shankaracharya, The Crest Jewel of Wisdom
Not only did the Sun itself produce cave and fire and moving shapes, and the shadows, and their beholders, but in doing so it manifested a property of its own nature not less essential—even more excellent—than that pure radiance upon which no earthly eye could steadfastly gaze. The shadows were as needful to the Sun as the Sun to the shadows; their existence was the very consummation of its perfection.
The baseball player Yogi Berra is reported to have said, "You've got to be careful if you don't know where you're going because you won't get there." That quirkily stated truth might be paraphrased as "You've got to be careful if you don't know who you are because you won't be yourself."
I have wanted to write a know-who-you-are book ever since Ancient Wisdom—Modern Insight 
was published in 1985. In that book, I drew on both Theosophy and contemporary knowledge for an overview of what the cosmos is and where it is going as it takes us along for the ride. Since then, I have wanted to expand on its chapter about who it is that's taking the ride and why we are doing so anyway.
It has taken me many years to find the time to turn that wish into reality. But those years have seen an explosion of consciousness studies in a number of fields. Psychology has plumbed new depths of the psyche and spirit. Psychotherapy has worked with even the highest reaches of human consciousness. Meditation has become readily available at many depths. We have never had a richer climate in which to explore human nature.
I have plucked some fruits from this plentiful tree and tried to share them in simple and lucid language. "To write well," Aristotle said, "express yourself like the common people but think like a wise person." The reader must be the judge of what wisdom is in this book, but I believe that I think like a Theosophist and hope I have conveyed some part of Theosophical wisdom. Theosophy offers an accurate and detailed map of all that we are, but we ourselves must explore the territory that the map represents.
In recent years, my own exploration has been in the study of Buddhism and the practice of Buddhist meditation. That influence pervades this book, which is less metaphysical and more experiential than Ancient Wisdom—Modern Insight. I believe, as did the Buddha, that to be ourselves and to find our way, we need to know who we are. Seeking self-knowledge is not a waste of time or selfishness but down-to-earth and practical. It has results in the world. As Swami Nikhilananda says in the preface to his translation of Shankaracharya's Self-Knowledge : "Self-knowledge is vital. All other forms of knowledge are of secondary importance; for a man's action, feeling, reasoning, and thinking are dependent on his idea of the Self" (xv). He goes on to say that if people believe themselves to be material creatures, they will follow a selfish ideal of material happiness and pleasure. If they believe they are spiritual entities with material bodies that should be used for spiritual ends, they will follow a path of love and unselfishness and promote peace and happiness for all.
If we explore our stream of consciousness, we find both material and spiritual levels, from the densest physical to the empty fullness of the highest spiritual, from the fragmentary and separative levels to absolute unity. We find familiar powers such as thought, emotion, and intuition all interblended into a structured whole, with every part interacting with all the others. We find a whole universe within ourselves, for as the Chandogya Upanishad says, "Even so large as the universe outside is the universe within the lotus of the heart. Within it are heaven and earth, the sun and the moon, the lightning and all the stars. What is in the macrocosm is in the microcosm also" (Prabhavananda, The Upanishads, Breath of the Eternal 74). And at the heart of this inner universe, as with the outer one, we find we are one with a divine field of consciousness, with Brahman or God.
So returning to Yogi Berra's wisdom, finding out who we are is finding out where we are going. We are on our way home, to our inmost roots, to realization of our oneness with all. And we will get there, for our final destination is what we already are but only need to discover.