The first book that everyone should own is Brewer's Guide to Phrase and Fable. It is a dictionary but not of individual words rather of expressions and places, persons and things in stories. A sample entry would be:
" Brigadoon. A fictional ghostly village in the Scottish Highlands which, in the eponymous whimsical musical comedy (1947) by Alan Jay Lerner and Frederick Loewe, comes to life only for one day every 100 years. A film was made of the musical in 1954, starring Gene Kelly and Cyd Charisse. The name is no doubt based on that of the River Doon in Ayrshire; brig means 'bridge'."
or this one,
"Plantagenet. A name commonly given since the mid-17th century to the royal line now more properly called ANGEVIN and to the LANCASTRIAN and YORKIST kings from Henry II to Richard III. these were the descendants of Geoffrey, Count of Anjou, and Matilda, daughter of Henry I. It may have arisen from Geoffrey of Anjou's habit of wearing a sprig of BROOM (plante genet) in his cap, or from the fact that he planted broom to improve his hunting covers. Henry II was Geoffrey's son....."
Where a word is all capitalized, there is a further entry in the Guide.
A second book that is de rigeur is Pliny the Elder's Natural History. It is rarely published in its entirety. My copy, which is a Penguin publication with John F. Healy translating, has only a selection. It seems clear to me while reading Umberto Eco's Baudolino that he has read Pliny as well since he places manticores in India just as Pliny has. Much of Baudolino's fabulous trip to find Prester John comes from Pliny, among other sources.
Amusingly, at the end of the entry on 'The Legendary Manticore, Basilisk and Werewolf', Pliny wrote "It is astonishing how far Greek gullibility will go. There is no occurrence so fabulously shameless that it lacks a witness."
Pliny died in the eruption of Vesuvius that destroyed Pompeii and Herculaneum. He was in charge of the fleet at Misenum and crossed the bay when the volcano erupted partly through scientific curiosity and partly to rescue survivors. His nephew and heir wrote about his demise and provides a record of the eruption of Vesuvius viewed at a safer distance. There are so many interesting bits in Pliny; how does one select just one as a sample?
Although it is just one among many, this one has its charms:
"The Magi. The Magi have certain subterfuges: for example, the gods neither obey nor appear to those with freckles. Was this perhaps why they stood in Nero's way? Tiridates the Magus ....refused to travel by sea, for the Magi consider it sinful to spit into the sea or defile its nature by any other human function......Although Tiridates had given Nero a kingdom, he was unable to teach him the art of magic. This should be sufficient proof that magic is execrable, achieves nothing and is pointless.....I met Apion the grammarian, who informed me that the herb cynocephalia, know in Egypt as osiritis, was a source of divination and a protection against all black magic, but that if anyone completely uprooted it , he would immediately die. He added that he had summoned ghosts to inquire from Homer his native land and the name of his parents, but did not dare to reveal the answer he had allegedly been given."
Interesting? I would like to know what everyone had against red-haired and freckled people. Really, I do.
The third book I would like to recommend is not really a book. It is anything by Aristotle. Poetics in particular is useful for English essays. With my pronouncement that "everything tastes better with bacon on it", I would also add "when your essay is too short, quote Aristotle". I have had a couple of professors get a little annoyed about the Aristotle quotes but, as long as it is relevant to the subject, they will not mark you down for it because you are quoting @#%&* Aristotle, fer cryin' out loud. If you are writing a high school paper, the teacher will probably be seriously impressed than you even know who Aristotle is. Although, I have to admit, Aristotle is not as interesting to read as Brewer's Guide or Pliny even if he is a super-philosopher.
So there you have it. My recommendations for any well stocked library.