Let’s start with the perpetual calendar. Lange has produced perpetual calendars before (even a Rattrapante Perpetual), so here we are getting a very finely tuned complication. The display is different though than with previous renditions. All four years worth of months, as well as the leap-year indicator itself, are contained in the subdial at 12 o’clock, while the day of the week is off the the left and the date off to the right. Down at 6 o’clock is the moonphase, nested inside the flying seconds.

There are cases to be made for and against displaying the months in this way. While the larger subdial does make it relatively legible, it’s certainly not as easy to read as a subdial with only 12 months. But, on the other hand, there is something poetic about seeing the entire cycle. But, unlike most perpetual calendars that use these hand-and-register displays, the markings do not drift by continuously. Only the moonphase is in slow, constant motion – the other indications all jump instantaneously at midnight, yet another way in which the Grand Complication shatters expectations.