The metaphor processing that this snowclone induces is more complex than most: in order to understand any given instance, you have to know what Z is, have an idea of how X relates to Z, and what about Y is important enough to illustrate the relationship between X and Z. Mark Liberman calls this “conceptual universe” a key element of the snowclone in “Snowclones are the dark matter of journalism“:
X is the dark matter of Y is more than a fixed phrase or cliché. It’s a pointer to a little conceptual universe, bringing along with it a metaphorical framework that structures the surrounding chunk of discourse. If X is the dark matter of Y, then X is crucial to Y, is even the biggest part of Y, but it is not directly visible, and must be inferred because of the strong effects it has on visible things.
(I have been more flexible in my definition.)
So, if you know what Y is, but are not as familiar with X and Z, use of this snowclone may give you a better idea of what X and Z are. This helped me understand “Eric Raymond is the Margaret Mead of the Open Source movement”. I sort-of know who Eric Raymond is and what Open Source is about, but now I understand his role in OS better, because I know who Margaret Mead is. This helps demonstrate the “thoughtfulness” this snowclone requires both from its user and hearers.
Examples of this snowclone abound, but I have no idea where to start for an earliest instance, if such a thing even exists. The metaphorical flexibility of this snowclone makes it much less idiomatically fixed than many of the others I’ve written about so far, which means you can’t trace it back to a comedian or movie from which all other usage was inspired. Metaphor is everywhere. It’s also very difficult to track down examples of the snowclone versus plain statements of the “Thing1 is the Thing2 of Entity” form. “The perfect is the enemy of the good” is not a snowclone, nor is “Jupiter is the lord of the house of Death”.
Other Language Log posts which talk about this snowclone include X as the Y of Z” and “