Wisdom and humility from Carl Sagan:
Humans may crave absolute certainty; they may aspire to it; they may pretend, as partisans of certain religions do, to have attained it. But the history of science – by far the most successful claim to knowledge accessible to humans – teaches that the most we can hope for is successive improvement in our understanding, learning from our mistakes, an asymptotic approach to the Universe, but with the proviso that absolute certainty will always elude.
We will always be mired in error.
-Carl Sagan, Demon-Haunted World, location 627 in the Kindle edition.
For my own thoughts on this kind of capital-C Certainty, see here, here, here, and here.
Inertia Wins! 