"A horse does not move like a goat:" Lothar Meggendorfer's magnificent mechanical books

"One of the collections we received that is most exciting to me is actually one that will be new to us altogether," Rosenbach director Derick Dreher said of the 76 late-19th- and early-20th-century pop-up books by the German artist Lothar Meggendorfer. At one time, Meggendorfer was enormously popular, with more than a million of his books in circulation.

Today, copies of his books are rare, with those in relatively pristine condition, as these are, even more rare.

"His work was extraordinarily fragile to begin with, and given the use of these items by children, few have survived," Dreher said. "[Maurice] Sendak may have owned the largest collection in the U.S., and it is now at the Rosenbach in its entirety."

Sendak was a huge fan of Meggendorfer's, calling him the "supreme master of animation" in the way that "every gesture, both animal and human, coarse and refined, was conveyed via the limited but, in his hands, versatile technique of movable paper parts."

The gestures, Sendak noted in a 1975 essay, were "precise and totally convincing for each individual creature. A horse does not move like a goat."

One book in particular, the Internationaler Circus, stands out -- and up. It does not function merely as a traditional pop-up book. Rather, its panels are unfolded to form a semi-circle, and risers full of performers and spectators fold down. Colors are heightened, figures seem spring-loaded, and the facial details on the dozens of figures are so highly developed you believe each must have been modeled on a real person.

"There are other Meggendorfers that fold out, but this is the only one where you get this sense of space. In that sense, it's his masterpiece," Dreher said.

Sendak admired something in Meggendorfer that also expresses how Sendak fans felt about him. Meggendorfer, Sendak said, never condescended to children because, in fact, children observed life more cannily than adults.

"It is no accident that children delighted in his work," Sendak wrote, "as did the adults who had the grace to remain children."