Quotations by:
Feather, William
An education isn’t how much you have committed to memory, or even how much you know. It’s being able to differentiate between what you do know and what you don’t. It’s knowing where to go to find out what you need to know, and it’s knowing how to use the information once you get it.
William Feather (1889-1981) American publisher, author
(Attributed)
The original source for this has not been found. It is quoted (without source) in Carman Fish, "The Safety Valve" column, National Safety News (1960-01). Prior to that, it is also quoted in Telephony Magazine, Vol. 150 (1956), p. 23 (but that article itself notes it is quoting from an issue of Copperweld Magazine).
The first two sentences are often credited to Anatole France, but this seems to be a fairly recent (1990s?) misattribution.
Another variant (attributed to France, uncited; e.g.): "True education is the ability to discern the difference between what you do know and what you don't."