Full Idea
To know yet to think that one does not know is best.
Gist of Idea
To know yet to think that one does not know is best
Source
Laozi (Lao Tzu) (Daodejing (Tao Te Ching) [c.530 BCE], II.LXXI.173)
Book Reference
Lao Tzu: 'Tao Te Ching', ed/tr. Lau,D.C. [Penguin 1963], p.133
A Reaction
Tricky. Self-deception doesn't sound like a virtue to me. There are epistemic virtues, and caution about one's own knowledge has to be one of them, but a totally false assessment sounds counter-productive.