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。

Te Ching Chapter Seventy-one

One who knows what people do not know,

Is a person of enlightenment.

One who pretends to know what he is ignorant of, is at fault.

He who is aware of what he does not know, shall not be at fault.

Therefore, a saint is flawless for he is aware of what he truly knows and what he knows not, hence he is flawless.