It's commonly taught in schools that Caligula was a madman. He appointed a horse to the senate, etc.

I heard recently, however, that Caligula did these things as a way of mocking the senate, and that it was intended as satire. Years later, however, the joke is lost, and out of context Caligula appears insane.

Sounds a bit dubious to me, but I figured why not go to the experts?