To know yet to think that one ...

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.
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.

More phrases

Effort only fully releases its reward after a person refuses to quit.
Never complain and never explain.
A good plan violently executed now is better than a perfect plan executed next week.
 George S. Patton
Problems are not stop signs, they are guidelines.
 Robert Schuller
Never give up, for that is just the place and time that the tide will turn.
 Harriet Beecher Stowe

Quotes from the same author

New beginnings are often disguised as painful endings.
He who controls others may be powerful, but he who has mastered himself is mightier still.
He who knows others is wise. He who knows himself is enlightened.
One who is too insistent on his own views, finds few to agree with him.
Kindness in words creates confidence. Kindness in thinking creates profoundness. Kindness in giving creates love.