The truth does not set you free. Only outrageous lies can do that.

Taylor and Brown argue that positive illusions are adaptive, since there is evidence that they are more common in normally mentally healthy individuals than in depressed individuals. However, Pacini, Muir and Epstein (1998) have shown that this may be because depressed people overcompensate for a tendency toward maladaptive intuitive processing by exercising excessive rational control in trivial situations, and note that the difference with non-depressed people disappears in more consequential circumstances.

-http://en.wikipedia.org/wiki/Illusion_of_control