Well, today Darby finally figured out that the dog door is a two way device that both lets him in from the cold and also magically transports him from the house to the back yard. It started out this morning with me forcing him out the door and then him spinning around and staring at me through the sliding glass doors as if I had insulted him. Then about an hour later he came into the office and acted like he wanted out, so I pushed him through again.
About 30 minutes later he appeared in my office, started playing with Remy, and then Remy took off for his secret exit. Darby stopped, ran to the glass door, and then barked through the glass at Remy who was standing on the deck just looking back at him as if he had won some battle. Then, Darby barked, ran over to the dog door, pushed it with his nose, and then out he went. Remy was completely surprised and took off running through the yard as Darby seemed to prance in joy and then remember that he was going through the door for the purpose of finding Remy. They played and chased each other with Remy having no place to hide. And, like all dogs that first discover the doggy door, Darby spent the next 30 minutes running inside and outside experiencing the magic of transportation from inside to out.