Watership Down is a book about rabbits. This, more or less everyone knows. Some will also be aware of the 1978 feature film, and some of the much more recent animated TV series, though neither approach the outstanding quality of the original novel. However, many people, upon discovering the bare bones of Watership Down's plot, dismiss it as "kid's stuff" and turn to something (as they see it) more suitable for an adult audience. They don't know what they're missing.

So I'll tell them now.

It's only fair to mention at this point that I'm a fur. If you'd like to know in detail what this implies, then you can read my essay Rabbiting On, but in essence it means that I have a particularly deep and intense empathy with animals. No prizes for guessing which sort, in my case! That cuts both ways, though - I love to read anything I can find about rabbits, but get very easily irritated by negative depictions of the species. Anyone who knows even a little about good old Oryctolagus cuniculus will know that their common depiction as "ickle fluffy bunnikins" is a million miles from the truth. They're tough creatures - they have to be - and it's a rare book that reflects that.

Thankfully, Watership Down is that rare book. Richard Adams had the sense to check the draft of his novel against RM Lockley's The Private Life of the Rabbit before publishing, and the research paid off. Maybe not every last detail is exactly correct, but it's a damn sight closer than anything else you'll find in the genre. Because the details of lapine life are so well described, they never feel awkward, and allow the epic tale to unfold smoothly.

The plot, in essence, is a simple and well-worn one. Visionary young buck Fiver foresees the destruction of his home warren in Sandleford, and attempts to warn the Chief Rabbit. However, he is rebuffed, and only a small handful of bucks are prepared to venture out into the unknown, among them Fiver's brother Hazel and Bigwig, an officer in the Owsla (a sort of lapine Praetorian Guard). They travel through dangerous lands, encounter other warrens, and generally have the sort of adventures you'd expect in such a novel. Along the way, Hazel gradually emerges as a natural leader, and it is this which is really the central theme to the book.

However, all this is done with a quite extraordinary respect for Nature - Mr Adams' descriptions of the Hampshire Downs (Watership Down, like all the other locations, is a real place) are superbly evocative, and bring out perfectly the sense of the southern English countryside. A reviewer of his second novel, Shardik (not nearly as good as this) said that it was as though he lived in the earth alongside the roots and bulbs, and I can see what was meant by that. All the knowledge of local flora and fauna is Mr Adams' own, and his love of the area comes through clearly.

Watership Down is, for some reason, mostly marketed as a children's book in Britain, although - like Philip Pullman's His Dark Materials trilogy, it is also available in adult imprints. This treatment of Watership Down primarily as juvenilia is not reflected in most other countries, where it is recognised on its own merits. Actually, I don't think that the divide between adult and children's fiction is much more than artificial in any case, and this book shows just why that should be.

This is a long book, and that allows the characters to develop more subtly than is usually the case in "children's" books. This has led some critics to complain that the rabbits are in the two-dimensional "cookie-cutter" mould, but they clearly haven't been concentrating. I defy any reader to tell me that Pipkin, for example, is the same rabbit in chapter 50 as he is in chapter 1. It's a quite ridiculous assertion.

The length also allows Mr Adams to build up a convincing and coherent culture and mythology for the rabbits,enhanced by judicious use of the Lapine language. Again, this is introduced gradually, so that when, in a particularly dramatic moment, Bigwig utters an entire sentence in Lapine, it seems the most natural thing in the world. We also hear wonderful tales of the legendary trickster El-ahrairah, whose name translates as "The Prince with a Thousand Enemies". Anyone who knows the works of Joseph Campbell will find a resonance in that, and indeed Messrs Campbell and Adams became good friends after Watership Down was published.

Two criticisms are often levelled at this book. And it's those eternal twins, sex and violence, that are the issues. Sexism is a charge which is often made - after all, the initial band from Sandleford is entirely male. But it's not really a fair criticism, for two reasons. For one, such wandering bands of rabbits generally are all-male, as RM Lockley tells us, and as Watership Down goes to great lengths to fit in with real rabbits' physical behaviour, it would be gratingly ill-fitting to change that. And secondly, anyone who thinks there are no strong female characters in the book should try mentally removing Hyzenthlay from the equation. Do that, and the whole edifice collapses at once.

Violence is another matter, though: this is a very violent book; there's no getting away from that. The somewhat hackneyed phrase, "Nature red in tooth and claw", really does apply here. The mortality rate for real rabbits is something like 90%, and while our heroes don't suffer to that extent, there is an awful lot of blood around. Rabbits are shot, snared, gassed, killed by stoats, maimed by other rabbits, and so on. Yet it never feels remotely gratuitous. Richard Adams is simply telling it like it is: a rabbit's life is a hard, dangerous one, full of fear and dark.

The whole book is laced through with wonderful humour. I confess to being utterly at a loss to understand those who claim the book is "humourless" - it's side-splittingly funny at times. Yet perhaps they say this because they are remembering the deeper, more affecting parts, of which Watership Down has so many. There are passages within that are among the most intensely moving in all of English literature, and in this vein the Epilogue is a quite astonishing tour de force.

Each literary genre has one, maybe two, books, that are generally felt to be of such quality that fans can point to them and say, "this is what it's all about." The Lord of the Rings. Jane Eyre. Foundation. In the field of anthropomorphic fiction, Watership Down stands proud as undisputed champion. There really is no excuse for not having read "that rabbit book".