I was shopping at my favourite local used bookshop recently and stumbled upon A Guide to Tolkien by David Day. Originally published by Mitchell Beazley of Octopus Publishing Group in 1979, and then republished by Chancellor Press in 2001, this 260 page book is a reference book with citations for fans of Middle-earth. I don't recommend this book, and it turns out to be a sort of re-hashed conglomeration of previous books Day published back in the 1970s. The problem with the book is that's filled with little inaccuracies, stated so casually that they appear to bear the same weight as all the other information in the book. All it takes is for you to catch one error, and then everything else is called into question. That's a pretty good summary of the book, as it turns out.
When I first perused the book, everything seemed to be in order. I don't know how many entries there are in the book because I chose not to spend my time counting each item in the index. There is an index of citations, which in a way compounds the confusion over the author's inaccuracies.
Here's a seemingly simple example. Day writes of Goldberry:
She was a golden-haired and beautiful nature spirit who may have been a Maia.
In the back matter of the book, he cites The Adventures of Tom Bombadil and Lord of the Rings as sources for Goldberry. Neither The Adventures of Tom Bombadil or Lord of the Rings explicitly states that Goldberry is a nature spirit, and there's absolutely no indication anywhere in Tolkien's writing that she is a Maia. As I understand it, many Tolkien fans do assume that Goldberry is a nature spirit, but it's probably most accurate to say that Tolkien fans assume that Goldberry is a reference to nature spirits in traditional folklore. Whatever fans believe, the fact is that Tolkien never classified Tom Bombadil and Goldberry in definitive terms. We don't know their species or genus, and we don't know whether Tolkien had even decided what those would be.
Day might believe, personally, that Goldberry was a nature spirit, and he might allow in his own head-canon that she may have been a Maia, but fan theories oughtn't appear along with verifiable data (such as the fact that she has golden hair and that she aided the Hobbits) without qualification. A less academic tone would have gone a long way, here. Imagine this revision:
To me, Goldberry is a nature spirit. Given the mysterious way Tolkien writes about her, I even wonder whether she may have been a Maia. What we do know for certain is that she is a beautiful, golden-haired, River-woman's daughter, slender as a willow-wand. She is the partner of Tom Bambadil, and is present when he brings the hobbits home after rescuing them from Old Man Willow.
Separate the fan theory from the written "facts," and there's no room for doubt. By mixing his theories or impressions with words that Tolkien himself wrote in published books, it's impossible to tell one from the other.
The Goldberry example is just one example, and it's arguably relatively minor. After all, it does seem like most fans believe that Goldberry is a nature spirit, so do we really have to use extra words like "may have been"?
Well, to be accurate, yes we do. Tolkien never wrote that she was a nature spirit, so if you're reporting on what Tolkien wrote then it is wrong to say definitively that she was a nature spirit.
OK, but the Maia thing is pretty minor, because Day does use the words "may have been" to clarify that he's not saying definitively that she is a Maia.
Well, except that he doesn't clarify whether "may have been" is a phrase he's using, as a reporter on Tolkien, or whether it's a phrase that Tolkien used. There's a huge difference between those 2 sources. If Tolkien said that she may have been a Maia, then canonically she may have been a Maia (he never said that, to be clear.) If Day said it, then it's a fan theory and has no place, at least without qualification, in a report on Tolkien's work.
What other fan theories lurk in the pages of Guide to Tolkien? It's hard to know, and that's exactly the problem. Once you realise that Day doesn't differentiate between his own impressions of Tolkien's work and Tolkien's actual work, you can't read Day's documentation of Tolkien without fact-checking literally every claim he makes, which frankly defeats the purpose of a reference book.
It's a real pity that Guide to Tolkien has turned out to be a questionable resource, because basically I appreciate this kind of effort. There's a lot of Tolkien lore, and it's spread throughout a lot of different books by different scholars. The best place to start is with Christopher Tolkien's works, but those can be verbose. I wouldn't mind have a reference book with just the essential data about major characters, locations, and events of Middle-earth. The frustrating thing about Guide to Tolkien is that it would have been easy to fix, just by writing with transparency and honesty. An author's voice could have clarified much, and helped the reader retain confidence in the book. However, Day writes the book as if it's just reference material, carelessly inserting his own pre-conceptions about Tolkien's work as if they were verifiable fact. I do not recommend Guide to Tolkien or any "reference" work by David Day about Tolkien and Middle-earth.