知不知，尚矣；不知知，病也。圣人不病，以其病病。夫唯病病，是以不病。
To know yet to think that one does not know is best;
Not to know yet to think that one knows will lead to difficulty.
It is by being alive to difficulty that one can avoid it.
The sage meets with no difficulty.
It is because he is alive to it that he meets with no difficulty.
“To know when one does not know is best.
To think one knows when one does not know is a dire disease.
Only he who recognizes this disease as a disease
Can cure himself of the disease.
The Sage's way of curing disease
Also consists in making people recognize their diseases as diseases and thus ceasing to be diseased.
To know and yet (think) we do not know is the highest (attainment); not to know (and yet think) we do know is a disease. It is simply by being pained at (the thought of) having this disease that we are preserved from it. The sage has not the disease. He knows the pain that would be inseparable from it, and therefore he does not have it.