The idea of understanding the past through the things that people made is obvious enough. That’s what museums have always done and lately, it’s been the subject of books that examine particular eras through a healthy example of artifacts. The Middle Ages in 50 Objects is a handsomely designed book whose full-color panels trigger texts that expand into the larger context of the items at hand. With everything from a Byzantine button to a Frankish brooch, an illuminated page from the Koran to a Roman Catholic altar front, the collection of objects (drawn from the Cleveland Museum of Art) spans a wide geography and several distinct civilizations. Missing, the authors admit, are Jewish artifacts from the period, a gap in the museum’s collection explained in part by the destructive waves if persecution endured by the Jews.