I don’t really think old Laozi actually ever said this. But, it is a great quote. Related articles John Cage: Silence yet not silencing (pilimi200.wordpress.com)
#71* To know your ignorance is most upright.  Not knowing but pretending to know is illness.  Just consider shortcomings only as shortcomings: thus, no shortcomings.
#11* Thirty wheel spokes sharing one hub. The empty space in the middle has the usefulness to a cart. Knead clay to make a vessel.
#20* Sincerity’s “yes” and Flattery’s “yes”: How much difference Is there between them? Good and evil, how much difference is there between them? What people
#9.* Holding and filling it up, no comparison to stopping it in time; Honing and sharpening it cannot remain for a long time. Gold and