An open mind

If you are on the path of truth you have to have an open mind, which means you have to be willing to believe absolutely anything. This doesn't mean you believe any theory is true, but you have to believe it is 'as if true'. This means, in practice, that you have to try and prove something is true, as it is impossible to prove a negative, and proving a negative means you don't believe it, and if you don't believe something then your mind will:

1). Operate the self-fulfilling prophesy principle.

"In the province of the mind, what one believes to be true is true or becomes true, within certain limits to be found experientially and experimentally. These limits are further beliefs to be transcended. In the mind there are no limits."--John Lilly

2). Operate the ego denial principle, ego being the opposite of truth. The ego throws up a smokescreen which comes down to a). Rationalizations, such as all or most replacements are just 'surgery'. b). Ad Hominem attacks, you are mad, being the usual. c). Laughter. Don Juan said seers have to laugh at the Nagual otherwise it would drive them mad. Laughing at someone is also an ad Hominem attack.