知不知,尚矣;不知知,病也。
1To know and yet (think) we do not know is the highest (attainment); not to know (and yet think) we do know is a disease.
圣人不病,以其病病,夫惟病病,是以不病。
2It is simply by being pained at (the thought of) having this disease that we are preserved from it.
3The sage has not the disease.
4He knows the pain that would be inseparable from it, and therefore he does not have it.