Art historians broadly agree that the overall structure was designed and built by Hubert in the early 1420s, and that most of the panels paintings were completed by his younger brother Jan between 1430 and 1432. Yet there has been considerable debate, and many art historians, especially in the mid 20th century, attempted to attribute specific passages to either brother. However no convincing separation of their contributions has been established. A now lost inscription on the frame stated that Hubert van Eyck "maior quo nemo repertus" (greater than anyone) started the altarpiece, but that Jan van Eyck—calling himself "arte secundus" (second best in the art)—completed it in 1432. The original, very ornate carved outer frame and surround, presumably harmonizing with the painted tracery, was destroyed during the Reformation; it may have included clockwork mechanisms for moving the shutters and even playing music.