John_Charles_Webb said:
I believe the solution to the koan is:
By thinking I have brought myself into existence.
"When the inner dialogue stops, the world disappears"
Don Juan (Carlos Casteneda)
Rade said:
No, when "your" inner dialog stops, "your" world disappears, but the "world" does not disappear. Thus, when existence disappears, then the inner dialog will stop, and not a moment in time before.
You guys are so far off the mark about Zen and Don Juan it's funny

. You can't just twist around things to fit your personal philosophies.
Although JCWebb's final interpretation of Decartes is correct, 'cogito ergo sum' is not a koan; in fact, it is the opposite of a koan. It is the result of a logical process (decidedly anti-koan), a conclusion Decartes reached about what it is that one cannot doubt. After all, if one doubts thinking, there is still something left that is thinking doubt. For that reason Decartes decided he must possesses a fundamental trait whose nature it is to think.
Decartes must have been right about possessing something that thinks, but what justifies concluding the thinking thing is what gives consciousness existence? Decartes' reasoning is, as kant (PF's kant) pointed out earlier, a bit self referential. It's like radio that is always broadcasting a talk show concluding it exists because that talk show never stops. Is a radio more than what it broadcasts? Isn't it possible that the only reason the radio concludes what it does is because it
cannot stop that damn talk show from broadcasting?
Now for koans. A koan is not meant to initiate a logical process, normally it's an intuitive device. Consider this koan by the famous master Joshu, "A monk asked, 'Not being taken in by various things -- what is it like?' Joshu answered, 'It is, of course, how it should be.' The monk asked, 'Such is my true essence, isn't it?' Joshu answered, 'Taken in, already taken in.'"
How was the monk taken in? Well, the answer to that clearly disputes Decartes conclusion. The monk follows Decartes path and "thinks" about his true essence, but Joshu reprimands him for trying to think it. Zen is a meditation discipline (at least it orignally was). In meditation the mind is stilled so that what awaits behind it can come to the forefront.
THAT, according to the Buddha's teaching and the Zen teachers who followed his teaching (not all did), is one's true existence . . . not what one thinks.
Regarding Castaneda and Don Juan, anybody who's read Castaneda knows the above interpretation of Don Juan's statement is about as incorrect as one can get. The major purpose for Don Juan's statement wasn't to say that stopping inner dialogue will cease existence, but to say that it will result in discovering it. Thinking, according to Don Juan (like every true Zen master who has existed) is not what brings one into existence, it is what obscures our true nature (well, not actually thinking, but he inability to stop it, which most people can't). His teachings to Carlos were specifically to help him learn to stop the the incessant inner dialogue.
As someone who practices, I can tell you that when one is really able to quiet the mind, existence is intensely accentuated, and one can do little but surrender to the power of the moment. It's only those who've never experienced that inner silence who speculate one ceases to exist without thinking, or that thinking engenders existence.