Every student at the Massachusets Institute of Technology is required to take certain core classes. One of these notorious freshman classes is 18.03, or Differential Equations, taught by one Hartley Rogers. According to rumor, Hartley is a direct decendent of William Barton Rogers, the founder of MIT, and there are students at MIT now whose parents took 18.03 from him when they were freshmen.

Hartley is one of those love-him-or-hate-him professors, and no freshman gets through the class without having at least one long debate about whether or not Hartley can teach. And that's just how it was when a pair of freshman hackers were sitting around in the Coffeehouse one evening tooling on some problem sets. One student would say "He's the worst professor I've ever had! He's boring, has terrible handwriting, and he can't explain anything!" And another would reply "What are you talking about? Hartley's great! He's the best teacher I've ever seen!" And the argument would continue. This gave them an idea.

A few weeks later, there comes a morning with a perfectly ordinary 18.03 lecture. Hartley is standing next to the board, writing with his oversized lecturer's chalk and muttering into the microphone. The students in the first rows are diligently taking notes, the students in the middle rows just as diligently passing notes, and the students in the back of the lecture hall are catching up on the previous night's sleep, when suddenly, the door in the back of the lecture hall bursts open and a figure comes running in. He's dressed head-to-toe in black, with a black fencing mask and a saber, and he races down the stairs on the side of the lecture hall, calling out: "Hartley Rogers! For too many years you have bored the freshmen, put them to sleep with your matrices and your differential equations, and I've come to put a stop to it! Defend yourself!"

Now Hartley Rogers is standing there looking astonished, and the students have all realized by now that there's something more interesting than mathematics going on. Before Hartley can reply, however, the other door to the lecture hall burts open and another figure comes running in. This one is dressed from head to toe in white, with a white mask and carrying a saber, and as he runs down the stairs into the hall he cries out "Hartley Rogers! For years, you have taught the freshmen well, and given them the tools they need to learn. I will defend your honor!"

And as the students and Hartley look on, the two fencers have a furious swordfight back and forth across the classroom. Finally the swordsman in white disarms the swordsman in black, and the two mysterious figures disappear again, and Hartley goes back to his lecture.