In the American Jungle by Waldo David Frank

In "The Comedy of Commerce," I referred to jazz, not in uncomplimentary terms, but critically as an instance of the art of a commerce- and industry-ridden people. Many readers gave protest. So far as I could see, the chief point against me was that I had dared be critical of a folk art. Jazz, went their sentimental plaint, was the expression of a people. (I had not denied it.) Hence, hands off! Hence, down on worshipful knees!

There has, indeed, been abroad for a full century the curious notion that folk art-as once the king-can do no wrong: that folk art is necessarily good art: that the critic who dares to question folk art commits the unpardonable sin.