Tao Te Ching: Chapter 71

1

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.

2

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.