The work Bentley did sounds very impressive and I in no way strive to downplay his archival achievements. I do however take offense with the semantics of the wording. Not finding an exception isn't what proving means. Or, as Dr. Carl Sagan put it: absence of evidence != evidence of absence.

Absence of evidence is evidence of absence. The correct saying is: Absence of proof is not proof of absence.

Overly pedantic

It seems like an important distinction. Evidence != Proof

It's a meaningless distinction.

I remember hearing about someone discovering two very similar snowflakes.

Ahh, found it. Nancy C. Knight, "No Two Alike?" Bulletin of the American Meteorological Society, 1988. https://journals.ametsoc.org/downloadpdf/journals/bams/69/5/... and available via https://scholar.archive.org/search?q=Nancy+Knight%C2%A0-+Bul... .

> Figure 1, a photograph of actual snow crystals, not replicas, illustrates a striking example of two snow crystals which, if not identical, are certainly very much alike. ...

The two very similar snowflakes are in the bottom center of figure 1, side-by-side.

Counterpoint https://qz.com/1208669/meet-the-scientist-who-makes-identica...