To get the ball rolling on rationality quotes, here's a rationality quote from the father of the Greek enlightenment, Xenophanes:

But as for certain truth, no man has known it, Nor will he know it; neither of the gods Nor yet of all the things of which I speak. And even if by chance he were to utter The perfect truth, he would himself not know it; For all is but a woven web of guesses

Enjoy your break.