On Doubt...

"Only those who doubt really believe, and those that do not doubt are neither tempted against their faith nor do they truly believe. True faith maintains itself in doubt; from the doubts which are its food it nourishes itself and conquers itself, moment by moment, just as true life nourishes itself on death and renews itself second by second, in a continuous creation.

A life without any death in it, without any unpiling in its continual piling up, would be a perpetual death, the repose of a stone. Those who do not die do not live; those who do not die at every instant, to rise from the dead on the instant, do not live; and those who do not doubt do not believe. Faith is maintained by resolving doubts, and again resolving those further doubts which are suggested by the resolution of previous doubts."

(Unamuno, Our Lord Don Quixote)