The smartypants of old used the obelus to call out chunks of text that might be somehow wrong, whether as a result of translation errors or info that was just plain bad to begin with. For example, there’s some debate about the Gospel of John’s Pericope Adulterae — the story where Jesus saves an adulteress from stoning by making her would-be punishers remember that they too have sinned. Although the story is one of the more famous of the New Testament, its authorship was questioned by the third-century scholar Origen, who marked the passage with an obelus. And yes, there is a certain irony to him being the one to find fault with the passage that gave the world that famous line, “Let he who is without sin cast the first stone.”
It should be noted, however, that it wasn’t always the ÷ that was written. A simple line could also be an obelus, as could the dagger symbol, or even the sign ./., which is sometimes called a lemniscus and which somehow evolved into the ∞, or the infinity symbol. (This symbol is properly called a lemniscate, and I wrote about it in a previous “word of the week” post.) In fact, there seems to be a great deal of overlap, both in form and name, with the division sign, the infinity sign and the symbols people use to say “Hey, this passage is wonky.” I am not clear why.