 If that second choice is the force book, it is handed to him; otherwise it, too, is discarded and the force book is handed to him.Although it is possible to extend this past three books, it becomes increasing obvious that a force is taking place if the force book is selected with the mentalist still holding multiple books.There are dozens of variations; Theodore Annemann's "Practical Mental Magic" describes fourteen in a single chapter and refers to more within the text.