Just as our visual system strains to see the vase and the two faces at once, we struggle to conceive of a motion that has a dual motivation: to put and to fetch. A paper by Van de Cruys, Wagemans and ...

Colorful illustrations and photos accompany step-by-step directions in two spiral-bound entries in the Paper Magic series. Paper Tricks by Alan Folder, illus. by Maureen Galvani, shows aspiring ...