I’m in the process of reading Robert Burton’s excellent new book:  On Being Certain (2008).

Burton offers a quote at the beginning of Chapter 3, the chapter being entitled “Conviction isn’t a choice.”  Here’s the quote:

It is no great accomplishment to hear a voice in your head.  The accomplishment is to make sure that it is telling you the truth.

[The quote is attributed to “A patient describing a near-death experience.]