
The first two sentences of this statement first appear as attributed to France in the 1990s, but the full statement is earlier attributed to William Feather, as quoted in Telephony, Vol. 150 (1956), p. 23 http://books.google.com/books?id=Wm0jAQAAMAAJ&q=%22being+able+to+differentiate+between+what+you+do+know%22&dq=%22being+able+to+differentiate+between+what+you+do+know%22&hl=en&sa=X&ei=qYJOU9dAzoXRAYumgcAP&ved=0CMsCEOgBMDQ
Misattributed