Never mind what you're burning to write
How are you going to get there?

Come back Mr Casaubon, all is forgiven

In putting together the list of Books for Writers, over there in Resources on the right-hand sidebar (which I keep adding to, and welcome more of your favourites in the comments), I realised that there's one kind of book I really, really wish someone would compile. There's nothing I enjoy more than a happy ten minutes (half hour... hour... Remind me what I was looking up?) pootling about in Brewer's Dictionary of Phrase and Fable, for example. But if I'm really in full, writerly cry, what I want is reverse dictionaries and encyclopaedias.

For example, as a word-nerd I might be idly curious about a piece of slang, either its origin or its meaning, but when I'm writing what I really, really want is something which where I can look up the polite word, and be offered a whole slew of rude ones, some of which I'll have thought of, some of which I'll be reminded of, and some of which will be new and delicious.There is such a book, for slang at least: Jonathon Green's Slang Thesaurus, but it's not in print and, compared to his magisterial Dictionary of Slang for Cassell, it's a slimmish volume, without dates, which are essential not just for hist-fickers, but for anyone tangling with anything as shifting in time and place as slang.

But where are all the other reverse reference books? The trouble is, it's incredibly difficult to find out anything in a reference book unless you already know what you want. Another example: the fundamental theme of A Twist of Gold which, if I wanted to sound pretentious I would say structures both character and action, is betrayal. By way of layering things up, looking for ideas to develop, texture, depth, resonance and just plain interesting oddity, what I wanted was an encyclopaedia in which I could look up 'betrayal', and get a Cook's Tour, or at least a run-down, of myths, legends, symbols and stories from all round the world. More light-heartedly, if would be handy to have a medical dictionary organised by degree of illness or type of disability, so I could decide how difficult I wanted my character's ailment to be to diagnose, or how hampered she might in getting about, say... and be led straight to an obscure disorder of the pancreas (Oooh, hereditary? So, how does that tie in with the fact that she doesn't know that her real father is... ) or the precise kind of broken fibula which will mean she's still on crutches for Christmas.

And don't tell me that the solution is online. Yes, the digital world has the merit that information can be arranged, rearranged, searched and sorted in different ways but, frankly, most of the information out there is so trivial, and so much a re-hash of what I already know, that it's very little use. At the very least you need access to the academic e-libraries for the scholarly reference works, and then the search tools can be pretty primitive. I was lucky with A Secret Alchemy, because when I googled 'Journeying in Greek Myth' I turned up Jason. I got a very thorough account of all the bits of the myth, in all its variations, and discovered not only that he did well for journeying and so by implication pilgrimage, but other things: that the Golden Fleece was a symbol of a peaceful kingdom; Elizabeth Woodville really was compared to Medea, as a symbol of evil motherhood; and at the end of his life Jason was killed by the magical keel of his own ship, which was named 'God Given'... so perfect for Anthony's last hours. (And then 'golden fleece' led me to Sir Walter Raleigh who wrote his magnum opus in prison as Malory did, and an order which Edward IV really was granted.) I tried to get Atalanta and her apples in, but didn't manage it, but thinking around apples led be to bury in a reference to the Garden of Eden. Indeed, Jason ended up being more important to the book than the Arthurian legends which I had started with. But I've tried it with other themes and other books and not got far at all.

It's not laziness. I do my best with the education I have, the TLS, notebooks for anything I fancy even if I don't know what I fancy about it, and a flypaper memory which seizes all sorts of random things and stuffs them away for later. But none of us can not only remember, but have ready to be recalled, everything which might be valuable, enriching or just plain fun, particularly if we want to go beyond the boundaries of our own culture and education. To a degree, I enjoy the randomness, the idea that if I hadn't found Jason the book would have been different. And I certainly wouldn't want to use my ideal, reverse encyclopaedia just to sprinkle in a few clever references over basic stupidity, or to create a trompe l'oeil profundity out of a few inches depth of plaster and paint. But as anyone who's ever pootled about in a really good reference book knows, as you learn new things, or are reminded of things you've forgotten, or reminded that things you know fit in more ways and places than you'd remembered, new ideas begin to form. Feelings spark off thoughts, and thoughts set off feelings, and before you know where you are, you're re-writing an ancient Greek myth as a day in 1900s Dublin...

I suppose it's one of the ways in which fiction-writers live life backwards. Most people take the spontaneity of an emotion as a guarantee of its authenticity; we decide what we need characters to feel, create situations to bring it about, and then work hard to make it seem spontaneous. Most people want to find out what happens; we spend our time making things up as if they have happened. Most people take facts as the immutable element of life; we use them to make our infinitely mutable fictional world convincing. And so, when most people want to look up a reference, and find it explained, we want to look up the explanation and find its embodiment, whether that's a golden fleece, or a very rude word...

Let's face it, what I want is Mr Casaubon's Key To All Mythologies. But what would your reverse encyclopaedia help you to find?