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.
ZhuangziHe who knows he is a fool is not the biggest fool; He who knows he is confused is not in the worst confusion.
ZhuangziThe perfect man uses his mind as a mirror. It grasps nothing. It regrets nothing. It receives but does not keep.
ZhuangziHeaven cannot but be high. Earth cannot but be broad. The sun and moon cannot but revolve. All creation cannot but flourish. To do so is their TAO. But it is not from extensive study that this may be known, nor by dialectical skill that his may be made clear. The true sage will have none of these.
ZhuangziWhen the shoe fits, the foot is forgotten; when the belt fits, the belly is forgotten; when the heart is right, "for" and "against" are forgotten. There is no change in what is inside, no following what is outside, when the adjustment to events is comfortable. One begins with what is comfortable and never experiences what is uncomfortable, when one knows the comfort of forgetting what is comfortable.
Zhuangzi