What does “Empedocles’ sandal” mean in terms of English usage?

Solution 1:

Wikipedia mentions the following:

Diogenes Laërtius records the legend that he died by throwing himself into an active volcano (Mount Etna in Sicily), so that people would believe his body had vanished and he had turned into an immortal god; the volcano, however, threw back one of his bronze sandals, revealing the deceit.

Although I cannot say I ever heard the expression used, I would assume, based on this description, that Empedocles’ sandal is the sign that gives away a deceit. I imagine it could be used in a sentence like this:

The credit card bill that he carelessly had left on the table for his wife to find turned out to be his Empedocles’ sandal; it revealed he had spent the weekend in a Paris hotel instead of working overtime at the office.