This is our 50th strip, so I celebrated by using a somewhat unusual speech bubble layout in panel 2.

Oh, see the flag in panel 4? The one that looks cool even though I didn't tape it to the wall perfectly? It was designed for us by Obdormio, on hearing that Stephen is a vexillographer. We'd been waiting for the right moment to work it into the strip.

We thought of this storyline in June, but you can't just derive things in any old order. You need to build off of your earlier proofs. This is what we call model-theoretic continuity, or logical canon. Between then and now, it had the status of postulate. Ben and I don't publicize our postulates, largely because we like to maintain a reputation of infallibility. Also, if we were pythagoreans or numerologists, we would be very excited that we could prove this as our fiftieth theorem.

One of my undergraduate professors told a joke about a blind guy and a swan my sophomore year at the Univeristy of Rochester. The joke made no sense at the time, because I didn't realize it connected up to something from the reading, and didn't really understand that thing anyways, so even if I had made the connection, I still wouldn't have gotten the joke. Then, like last year, I was at a philosohy graduate student get together thing, and someone was talking about this thing called the Molyneux problem. All of a sudden, the joke from three years prior made sense, which is one of the best humor-related experiences of my life. I wish more jokes were so complicated that I only got them on a three year delay after learning about a philosophical debate from the 18th century.

Here's the joke, but you don't get the explanation: A blind man walks into a bar, and there is a swan on the table. He listens to the swan, feels the swan's feathers, and smells it. "A ha" he anounced. "Now I know what whiteness is."