He looks at the ladder, up into the recesses of the stacks. So these are books, he's guessing from context. "... If I point to it, will you be able to tell me which one it is?"

Even as he asks, he rises up onto his hind feet, nearly twelve feet tall as he grips the shelves to steady himself. "Which ledge? This one, or higher, or lower?" he asks, touching the book at his new eye level.