Ben, I'd've thought you'd known me long enough to know that I'm familiar with RSA and the history of number theory. (Maybe I misremember; you seem to have started doing Perl after I left clpm.) I read A Mathematician's Apology last year (most of it, anyway), and my friend Nadia keeps publishing papers that factor large numbers of RSA keys in practice, the latest being CacheBleed. Your understanding of cryptography is surely deeper than mine — the most I've ever done myself is write an implementation of SRP — but it's not as if I haven't heard of the field.

I had thought that it was common knowledge that (small) prime numbers had a lot of practical uses (mental arithmetic in general, arithmetic with fractions, including with vulgar fractions, gear train design, that kind of thing) but apparently I was wrong. It turns out that lots of people don't know about this. So my inference, that only a complete idiot would not know this, he did not know this, and therefore he was a complete idiot, was ill-founded.

And so I came out looking like some kind of ignorant, arrogant know-it-all. I really appreciate the feedback, Ben. Natanael_L, I'm sorry I was such a dick to you.