Question Quotation: Voltaire - Judge a man not by his answers

One of the defining quotations for this blog is often attributed to Voltaire:
Judge a man not by his answers,
but by his questions.
French Enlightenment writer, historian and philosopher François-Marie Arouet who went by the name Voltaire (1694 - 1778).
But I wanted to know where and when he said this, and a quick search turned up...
Misattributed to Voltaire
It turns out this is likely not a saying by Voltaire afterall - Wikipedia says on the Voltaire quotations page in the Misattributed section:
Judge a man by his questions rather than by his answers.
...alternatively...
It is easier to judge the mind of a man by his questions rather than his answers
...and the original french:
Il est encore plus facile de juger de l'esprit d'un homme par ses questions que par ses réponses.
Which was actually written by Pierre-Marc-Gaston, duc de Lévis (1764-1830), Maximes et réflexions sur différents sujets de morale et de politique (Paris, 1808): Maxim xvii.
(Original photo AGO Sin and Salvation - the lean :: February 12, 2009 from my photoblog seemsArtless, text added using addText.com.)