Chapter 71 of the Tao Te Ching

Translation

To know yet to think one does not know is the height of virtue.
Not to know yet to think one knows is the sickness of men.
If you grieve for this sickness, you will not experience it.
The Sage does not experience this sickness because he grieves for it.
This is why he does not experience it.

Notes

The word bìng is used eight times in this chapter (which contains only twenty-eight words), either as a noun or a neuter verb. It is according to the commentator 河上公 Héshàng Gōng that I translated the 2nd and 6th bìng as "to grieve" ( "to find bitter, painful, distressing"), and the 4th, 5th, and 8th as "to be ill, to suffer from an illness"; 有病 yǒu bìng.

A: To know the Tao and to say that one does not know it is the height of virtue.

E: To be dazzled by the knowledge that arises from contact with sensible things, and not to possess the non-knowing that constitutes true knowing, is the common failing of men of this age. This is why, if he who knows the Tao can return to non-knowing, it is the mark of eminent merit.

In Chapter X, Laozi expresses the same thought when he says: 'If a man can free himself from the lights of intelligence, he will be exempt from all (moral) infirmity.'

E: He who does not know the Tao clings to false knowledge and takes it for solid knowledge. As soon as false knowledge resides in his mind, it becomes, for him, a sort of sickness.

E: False knowledge is the sickness of our nature. When one knows that false knowledge is a sickness and grieves for it (literally: 'and looks upon it as a sickness'), then one does not experience the sickness of false knowledge.

E: To know the Tao and (to believe) that one does not know it is precisely the business of the Sage. The Sage is exempt from the sickness of false knowledge because he grieves for it. This is why the sickness of false knowledge stays away from him.