The P.I.E. metaphor - 2

On dailykos.com alevei continued:

In my previous post, I wrote about coming to terms with the metaphorical nature of Proto-Indo-European (PIE), which may or may not ever have existed as an actual language spoken by actual people at an actual moment in time but that is posited to be the common ancestor of most of the languages of Europe and many in western and central Asia.

To recap, the gist of that post is that the Indo-European hypothesis is large and contains multitudes and that the options seem to be to accept the astonishing inexactness of the metaphors or submit to the paralyzing mind-blowingness of what we use them to try to explain. I suggested that the latter option could be inconvenient if you're trying to discuss historical linguistics and language relatedness in a class that meets for an hour and fifty minutes twice a week for 15 weeks.

Anyway, continuing on the topic of the metaphors that we use to try to create some kind of manageable order out of the chaos that is the story of human language and how it got this way, we turn now to a fellow name of August Schleicher (1821-1868), a German linguist by training and profession who specialized in classical and Slavic languages. Schleicher, who may have had some of the same concerns that I have about how we can possibly even try to conceptualize an unattested 5,000 to 7,000-year-old super-ancestor Ur-language that might not even have actually existed, decided that it was time someone got around to the task of trying to reconstruct Proto-Indo-European.
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....Anyway, in 1861, Schleicher published his reconstruction of PIE in a book called Compendium der Vergleichenden Grammatik der Indogermanischen Sprachen, known in English (and available in translation here) as A Compendium of the Comparative Grammar of the Indo-European Languages. Revisions and reissues appeared well into the 1870s, although Schleicher himself died in 1868 at age 47.

"What does all this have to do with metaphors?" you might be thinking. Everything. It has everything to do with metaphors. For one thing, even as Schleicher published his reconstruction of a 5- to 7,000-year-old dead language that might not have existed in the first place, he also made it clear that he knew all along that he was dealing in metaphors, and particularly in a big PIE-shaped metaphor, one that made it possible for him to reconstruct what was quite possibly a mythical language. As he wrote in the Compendium in 1861 (although of course he actually wrote it in German):

"A form traced back to the sound-grade of the Indo-European original language, we call a fundamental form. When we bring forward these fundamental forms, we do not assert that they really were once in existence." (Emphasis added.)