
April 18, 1775, p. 258
Life of Samuel Johnson (1791), Vol II
"A Third Kind of Knowledge" http://www.edge.org/q2010/q10_7.html#saffo, in The Edge Annual Question—2010: How Is the Internet Changing the Way You Think? http://www.edge.org/q2010/q10_index.html, January 2010
April 18, 1775, p. 258
Life of Samuel Johnson (1791), Vol II
Source: Four Seasons in Rome: On Twins, Insomnia, and the Biggest Funeral in the History of the World
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
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; the first two sentences of this statement began to be attributed to Anatole France in the 1990s, but without any citations of sources.
Source: The Boy Book: A Study of Habits and Behaviors, Plus Techniques for Taming Them
Source: Twitter post https://twitter.com/RoKhanna/status/1078458258833268736 (28 December 2018)
1974 speech, in Voices of Multicultural America: Notable Speeches Delivered by African, Asian, Hispanic and Native Americans, 1790-1995 by Deborah Gillan Straub
Interview in First for Women magazine (February 8, 2010, p. 46) http://jennifer-beals.com/media/press/first.html.