No other book is quite so completely and utterly worthless as a mediocre novel. A mediocre guide to trees or to cheese can have its uses for those who don't have anything better on the subject to hand. A history book or biography, however dull, contains some facts that may prove handy to somebody one day. Atlases, dictionaries, anthologies and instruction manuals, however uninspired, all have some little utility. But a lifeless novel has no value whatsoever.