Luke is a Page on the Library's staff. Among other things, he reshelves books, which is much more difficult than you might think. I can count the number of people I know who have mastered the Dewey Decimal System on one paw, and library pages must be masters to do this job. (Luke's sister, Anastacia J., also served as a Page at MPL. A family highly skilled in the Dewey arts. Like the Jedi arts, only without light sabers. Or Star Wars licensing fees.)
By the way, Luke needs a "Cauli name" that I will use when referring to him in my blog. Ordinarily, I pick these myself, but I'm going to break with tradition and let Luke pick his own "Cauli name." Of course, we could stick with Luke J, or Cool Luke J, i.e., a name like those rappers use. But it's his call. He knows where to reach me.