It is possible to read a book without comprehending the material, but then you are not really reading; the purpose of littérature is to transmit ideas, no matter if it is for sharing ideas, making a testimony to an event or simply to entertain. So if someones simply reads a book the way without putting the effort to understand the author's perspective and message, or the way his literary devices or poetry enlightens the text, then that someone as not understood a thing about his or her book, making his or her reading useless. Hope that makes sense...