So I've gotten nowhere for a long time. But as so often happens, just as I ask for help, new ideas start popping into my head. I got a hold of a copy of his collected works and searched for 'intelligence' (not a difficult strategy to come up with one would think...). Found it in the essay on Henri Beyle in Books & Characters from 1922. Leaving this up in case there is any interest, but I won't be offended if someone removes it.