Twentieth-century Indo-Europeanists (though not their nineteenth-century forebears) have confused the issue of genetic affinity, which derives from classification, with such traditional concerns of historical linguistics as reconstruction and sound correspondences. Once it is recognized that taxonomy, or classification, must precede these traditional concerns, the apparent conflict between the traditional view and that of Joseph Greenberg and his followers is seen to be illusory. And finally, a comparison of all the world s languages in this new perspective leaves little doubt that all extant human languages share a common origin.