I recommend Alan Watts' The Book: On the Taboo Against Knowing Who You Are (here's a pdf, if you like).

From the preface:

THIS BOOK explores an unrecognized but mighty taboo—our tacit conspiracy to ignore who, or what, we really are. Briefly, the thesis is that the prevalent sensation of oneself as a separate ego enclosed in a bag of skin is a hallucination which accords neither with Western science nor with the experimental philosophy-religions of the East—in particular the central and germinal Vedanta philosophy of Hinduism. This hallucination underlies the misuse of technology for the violent subjugation of man's natural environment and, consequently, its eventual destruction.

It demonstrates how our conscious attention (and our insistence that conscious attention is the only meaningful way to perceive ourselves and the world) creates an illogical but convincing illusion of ourselves as separate egos, contained within our bodies and existing independently of the rest of the universe. This passage sums up the central theme pretty well:

There are two ignored factors which can very well come into our awareness, and our ignorance of them is the mainstay of the ego-illusion and of the failure to know that we are each the one Self in disguise. The first is not realizing that so-called opposites, such as light and darkness, sound and silence, solid and space, on and off, inside and outside, appearing and disappearing, cause and effect, are poles or aspects of the same thing. But we have no word for that thing, save such vague concepts as Existence, Being, God, or the Ultimate Ground of Being. For the most part these remain nebulous ideas without becoming vivid feelings or experiences.

The second, closely related, is that we are so absorbed in conscious attention, so convinced that this narrowed kind of perception is not only the real way of seeing the world, but also the very basic sensation of oneself as a conscious being, that we are fully hypnotized by its disjointed vision of the universe. We really feel that this world is indeed an assemblage of separate things that have somehow come together or, perhaps, fallen apart, and that we are each only one of them. We see them all alone—born alone, dying alone—maybe as bits and fragments of a universal whole, or expendable parts of a big machine. Rarely do we see all so-called things and events "going together," like the head and tail of the cat, or as the tones and inflections—rising and falling, coming and going—of a single singing voice.

In other words, we do not play the Game of Black-and-White—the universal game of up/down, on/off, solid/space, and each/all. Instead, we play the game of Black-versus-White or, more usually, White- versus-Black. For, especially when rates of vibration are slow as with day and night or life and death, we are forced to be aware of the black or negative aspect of the world. Then, not realizing the inseparability of the positive and negative poles of the rhythm, we are afraid that Black may win the game. But the game "White must win" is no longer a game. It is a fight—a fight haunted by a sense of chronic frustration, because we are doing something as crazy as trying to keep the mountains and get rid of the valleys.

Sorry for the long quotations, but I think he does a much better job explaining himself than I would do for him. Reading this book as a teenager had a pretty profound impact on how I saw myself in relation to the world. It basically demonstrates how our feelings of isolation and disconnection from the world come into being, and that they are founded on logically unsound principles. Worth checking out, imo.