Query

Of late this blog's diet has involved a lot of mockery directed at cranks purveying bad law and bad history in the service of xenophobia and political opportunism. Perhaps a worthwhile endeavour, perhaps not, but it's time to return to our usual, and far more pleasant, fare of academic, philosophical, literary, and bibliographical trivia.

Somewhere, I read or heard the following smackdown: "A logician is a mathematician who knows the difference between use and mention." I cannot remember where, and I cannot find it on the internet. Can anyone help me?