Novelists have long tucked made-up fictions inside their real ones. Sometimes these interior texts inform the plot or enhance the theme, other times they are just lively bursts of color, sparks thrown off during the authorial process. It’s easy to understand the appeal of creating these miniatures. A few deft lines can conjure perfect examples of untutored rawness (Mattie Ross, the 14-year-old heroine of Charles Portis’s “True Grit,” has a manuscript entitled “You will now listen to the sentence of the law, Odus Wharton, which is that you be hanged by the neck until you are dead, dead, dead! May God, whose laws you have broken and before whose dread tribunal you must appear, have mercy upon your soul. Being a personal recollection of Isaac C. Parker, the famous Border Judge”), sublime dullness (“The Purpose of Clothing Is to Keep Us Warm,” in Jorge Luis Borges and Adolfo Bioy-Casares’s “Chronicles of Bustos Domecq”) or anything in between. Why write the whole book when you can get so much mileage out of the title alone?