Tao Te Ching Chapter 71

Who knows that he does not know is the highest;

Who (pretends to) know what he does not know is sick-minded.

And who recognizes sick-mindedness as sick-mindedness

is not sick-minded.

The Sage is not sick-minded.

Because he recognizes sick-mindedness as sick-mindness,

Therefore he is not sick-minded.

Tao Te Ching