is an excellent book by Paulo Coelho (isbn 978-0-7225-3293-5). As usual I'm going to quote from a few pages:
"This is the first phase of the job," he said. "I have to separate out the sulphur. To do that successfully, I must have no fear of failure. It was my fear of failure that first kept me from attempting the Master Work.
"But arms cannot be drawn unless they also go into battle. Arms are as capricious as the desert, and, if they are not used, the next time they might not function."
"I had to test your courage," the stranger said. "Courage is the quality most essential to understanding the Language of the World."
"It is not what enters men's mouths that's evil," said the alchemist. "It is what comes out of their mouths that is."
"Tomorrow, sell your camel and buy a horse. Camels are traitorous: they walk thousands of paces and they never seem to tire. Then suddenly, they kneel and die. But horses tire bit by bit. You always know how much you can ask of them, and when it is that they are about to die."
"There is only one way to learn," the alchemist answered. "It is through action."