"The  essay 'Sur le Commerce,' of [Jean-François] Melon, is the work of a man of sense, a good citizen, and an excellent philosopher. [...] There are, however, a number of errors in that excellent book; so great progress as he has made in the road to truth was no easy matter: it is a service done to the public to point out the mistakes that happen in a useful book. It is indeed in such only [that] we should look for them. It is showing respect to a great work to contradict it; a bad one does not deserve that honor."
--Voltaire, "On Commerce and Liberty" (1738), in Commerce, Culture, and Liberty, Henry C. Clark, ed. (Indianapolis: Liberty Fund, 2003): 277-8.