Here’s a letter that I sent this morning to the Wall Street Journal:
But while Mr. Spitznagel is correct that Keynesians ignored Mises’s 1912 book, Theorie des Geldes und der Umlaufsmittel  (and its 1934 English-language translation, The Theory of Money and Credit ), Keynes  himself did not ignore it – and therein lays a revealing tale.
When Mises’s German-language book first appeared in 1912, Keynes reviewed it in the prestigious Economic Journal, dismissing it as being unoriginal. Seems pretty damning, until we learn that Keynes himself, in his 1930 book Treatise on Money , confessed that “in German, I can only clearly understand what I already know – so that new ideas are apt to be veiled from me by the difficulties of the language.”
Keynes’s influential dismissal of Mises’s work was based not on anything as lofty as informed disagreement; it was based instead on incomprehension.
Donald J. Boudreaux