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.
ZhuangziTo regard the fundamental as the essence, to regard things as coarse, to regard accumulation as deficiency, and to dwell quietly alone with the spiritual and the intelligent - herein lie the techniques of Tao of the ancients.
Zhuangzi