Stealth Mysticism

There is a widely-accepted rule in hermeneutics called the Law of (or the Principle of) First Mention. I remember hearing about it in church when I was growing up, indeed hearing entire sermons based on a "truth" derived by the First-Mention Principle. I don't remember hearing it taught in the first Bible college I attended because they, somewhat tellingly, did not even OFFER hermeneutics (the last thing a hireling needs is someone being taught shepherding skills!). I was, however, taught this principle in a hermeneutics class in the second Bible college I attended.

But the more I reflected on it, this Principle of First Mention is a serious fallacy. Think about it: if the key to interpreting any person, place, thing, or idea in Scripture is to be found in its first appearance, this is the opposite of progressive revelation. The key to understanding redemption, for example, is not Genesis 3:15; it is the full exposition in Paul's writings. If the key to understanding lions is the first mention of a lion in the Bible, what exactly are we to learn from Genesis 49:9

          “Judah is a lion’s whelp;
          From the prey, my son, you have gone up.
          He couches, he lies down as a lion,
          And as a lion, who dares rouse him up?"

Are we to, upon later learning that Christ is the lion of Judah, teach that He had made sin and death His prey, and, let's see . . . He crouches, He lies down, so that refers to His resting after completing His work . . .

Oh, the sermons we could write. Oh, the ears we could tickle. The only problem is that NONE of that is in the Text! And the Principle is shown to be a quiet, stealthy infiltration, an unguarded back-door through which allegorizing and spiritualizing creeps in.

I'd be interested to learn the provenance of this First-Mention Principle. Who came up with this idea? Were they prone to spiritualizing the Text in other ways?

And are there other fallacies lurking in the methods we employ to prepare the weekly meal for His flock?