Standards are different for all things, so the standard set by man is by no means the only 'certain' standard. If you mistake what is relative for something certain, you have strayed far from the ultimate truth.
ZhuangziThe Portal of God is nonexistence. All things sprang from nonexistence. Existence could not make existence existence. It must have proceeded from nonexistence, and nonexistence and nothing are one. Herein is the abiding place of the sage.
ZhuangziWater becomes clear and transparent when in a quiescent stage. How much the more wonderful will be the mind of a sage when poised in quiescence! It is the mirror of heaven and earth, reflecting the ten thousand things.
Zhuangzi