This is great. Pretty similar to one by Mark Twain, actually, but I am adding it here, anyway:
"One of the saddest lessons of history is this: If we have been bamboozled long enough, we tend to reject any evidence of the bamboozle. We are no longer interested in finding out the truth. The bamboozle has captured us. It is simply too painful to acknowledge, even to ourselves, that we have been taken."