"Oh, it's simple to enlarge and reduce objects," Gale says. He doesn't mention that if he reduces them, his ability to enlarge them again is entirely dependent on how much magic he's already expended for the day. He doesn't prefer to remind others of the limitations of his magic, lest they decide that the cost of keeping him isn't worth it. "Here, may I?" He holds his hand out for the book. Once he has it, he reduces it down to an eighth of its size (and weight) and hands it back.