is an excellent book by Carlos Castaneda (isbn 978-0140192384). As usual I'm going to quote from a few pages
By experiencing other worlds, then, we see our own for what it is and are thereby enabled also to see fleetingly what the real world, the one between our own cultural construct and those other worlds, must in fact be like.
There is nothing wrong with being afraid. When you fear, you see things in a different way.
Fear is the first natural enemy a man must overcome on his path to knowledge.
You dwell upon yourself too much. That's the trouble. And that produces a terrible fatigue.
Are you angry at me don Juan? I asked when he returned.
He seemed surprised at my question.
No! I'm never angry at anybody! No human being can do anything important enough for that. You get angry at people when you feel their acts are important. I don't feel that way any longer.
What will happen to the man if he runs away in fear?
Nothing happens to him except that he will never learn.
He will never become a man of knowledge. He will perhaps be a bully or a harmless, scared man, at any rate, he will be a defeated man. His first enemy will have put an end to his cravings.
And what must he do to overcome fear?
The answer is very simple. He must not run away. He must defy his fear, and in spite of it he must take the next step in learning, and the next, and the next. He must be fully afraid, and yet he must not stop. That is the rule! And a moment will come when his first enemy retreats. The man begins to feel sure of himself. His intent becomes stronger. Learning is no longer a terrifying task.
When this joyous moment comes, the man can say without hesitation that he had defeated his first natural enemy.
Does it happen at once, don Juan, or little by little?
It happens little by little, and yet the fear is vanquished suddenly and fast.
But won't the man be afraid again if something new happens to him?
No. Once a man has vanquished fear, he is free from it for the rest of his life because, instead of fear, he has acquired clarity - a clarity of mind which erases fear. By then a man knows his desires; he knows how to satisfy those desires. He can anticipate the new steps of learning, and a sharp clarity surrounds everything. The man feels that nothing is concealed.
The freedom to choose a path imparted a sense of direction through the expression of personal inclinations.
Exertion entailed not only drama, but also the need of efficacy. Exertion had to be effective; it had to possess the quality of being properly channelled, of being suitable.
To become a man of knowledge was a task that could not be fully achieved; rather, it was an unceasing process comprising (1) the idea that one had to renew the quest of becoming a man of knowledge; (2) the idea of one's impermanency; and (3) the idea that one had to follow the path with heart.