It was so clever that I wondered out loud "how did she do that?" and turned over the page to discover a small slit made rigid with a careful application of black wax. The ship was attached by a pin which passed through the slot; the pin had a small black plastic cap that kept it in place. The mechanism was crafted so that the force of gravity caused a stately procession of the ship shortly after the page was lifted.

So that's how the letter worked, but how did the dream itself work? I won't ask what it "means," but, in general, how do dreams do what they do? Are there any patterns we can detect? If I could turn my dream over what kind of pins and slots would I find?

The basic pattern I sense is a dichotomy, two distinct and often opposing forces: the dreamer and the dream.

The dreamer is like a hobbled version of my waking "self." Perspectives in a dream often shift in bizarre ways - one minute I am watching a movie, the next I am in the movie, first as one character then as another - but there is generally a "me" in the dream. When people describe dreams they say "I did this. Then I saw that." Despite all the shifting imagery we perceive ourselves as being "in" the dream.

But the me in the dream is different from the me I experience in waking life. For one thing, I can't seem to think clearly in dreams. I've had dreams in which I struggle at great length with some simple mathematical problem; upon waking the answer is obvious. I sometimes try to take notes in my dreams but to no avail: the dream "me" cannot read. (I can "pretend read", that is, I can look at a newspaper or letter and seem to read a story, but I'm not actually seeing the words; even if I try to write I cannot see the actual words I've written.)

The dreamer is also naive, an easy mark for the silly plot lines and constraints of the dream. If the dream says I am late for class then I accept the situation without question and begin to madly rush about. The dreamer is easily manipulated and sometimes, like a little boy, reduced to tears by forces utterly trivial to the waking man.

Here lies both the peril and the power of dreams. All my adult skill and defenses are left behind when I dream. This means that I am at the mercy of my dreams and so face the real possibility of monsters and nightmares. But it also means that I am open to experiences which are automatically deflected by the habits of my waking self. The dream I had this morning allowed me to re-experience feelings long since repressed or forgotten. By day I analyze my feelings - by night I feel them.

The dream, on the other hand, plays with the dreamer like a cat playing with a helpless mouse. There is no stopping to think over the situation, no consideration of alternatives. And if the dreamer starts to resist, the dream changes to distract him, to keep him from waking. There is a constant struggle between dream and dreamer.

Who, or what, then, is this opponent? I am taking a bit of a leap here by presenting the "dream" as a single entity. But that is my experience. The images shift, but beneath it all I sense a singleness of purpose, a mind, a "dream-maker."

It's tempting to speculate that each of us has two minds, a "left-brain" and a "right-brain," and that, during the day, the left-brain is in charge. After all, the left-brain can speak; the right-brain cannot. Our human society functions primarily through words, not images. During the day the right-brain, every bit as deep and complex as the left, is forced to listen to the pontifications of its cellmate. At night, however, the left-brain's magical gift of language is stilled and the right-brain struggles for dominance. It's a life-and-death struggle that the right-brain inevitably loses each morning with the coming of the dawn.

I have no idea if the actual biological basis for dreaming supports this mythic left/right struggle, but as a metaphor it captures the two-sided contest I have experienced over the years. I think it is a struggle that makes many people uncomfortable with their dreams. Struggles, however, can sometimes be resolved.

In my metaphor, the left-brained dreamer is a helpless child and the right-brained dream a dangerous opponent. But over the years I have managed to educate and empower my child dreamer. I trained myself to resist and even pursue dream monsters. I began routinely flying off cliffs and swimming like a dolphin through dream rivers. Once the element of fear was removed I was then able to, in essence, make peace with my dream-maker by loosing the reins and letting it take me where it will.

After much practice I have become a fearless explorer of my dreams. But although I have made peace with my dream-maker I still find him (her? it?) utterly mysterious. Upon careful analysis I can often identify the materials out of which a dream is crafted: images seen in the last 48 hours, an overheard phrase, a revised prop from an earlier dream. But the dream itself is always foreign, full of things I would never imagine in my waking life, and is woven together not at random but according to some strange purpose. There is someone else in my head, someone I can only encounter in my dreams.