In the immortal words of Oscar Hammerstein, “A bell is no bell ’til you ring it,” and in this picture book, Barnes and Coelho make a similar case: a book is just a book until it’s opened. Each page is filled with fantastic illusions and meticulously detailed illustrations that demonstrate the many things that a book is not. A boy and girl are shown plunging into the pages of a book populated with wild gizmos, a fish-shaped submarine, a “cunning old shrew / with a bubbling brew / of lizard stew,” a sleeping dragon, and many other attractive oddities. Sumptuous illustrations in jewel-tone colors will draw viewers along to the end, where the point is clearly stated; the mysterious roundabout message will delight some and confuse others. “A book is a book / when all by itself, / when it’s closed and flat, / alone on the shelf.” When opened, it inevitably becomes much more.