It is perhaps a truism that every writer has a different process, and that every writer works in a slightly different way, but the publication over the last forty or so years of the previously unpublished and uncollected works of J. R. R. Tolkien has proven a treasure-trove for those interested in the ways in which writers compose, revise, review, and remake their fictional worlds. As both a fantasy writer and a reader, I have found the successive volumes of Tolkien's writings fascinating and heartening: even the most successful writers, it appears, take their work down blind alleys, discard material they find unsatisfactory and follow their characters through multiple transformations. I've been known to recommend the multiple volumes edited by Christopher Tolkien (and in particular those dealing with early versions of The Lord of The Rings) to writing students and those intending a career in fantasy or science fiction for precisely these reasons. The collected works of Tolkien have become a fine resource for studying a writer at work.

The present volume, however, is not by Tolkien, nor is it precisely about him. In their long and thoughtful introduction, the editors make clear that they are interested not in the sources of Middle-earth but the influences upon it. This may seem like a fine distinction, but it is an important one. Sources underpin a work, they shape it, they may even dictate it. Influences . . . well, they influence. They are frequently less directly apparent, both to the reader and to the writer as they work. They may be subtle, they may be distant, but their reach can be long and their effects deep and defining.

Tolkien's interest in what he called 'Northernness' and his academic career in the fields of Old and Middle English are well-known, as are their effects on his fiction. The Keys of Middle-earth presents readers with a selection of texts whose influences the editors have traced from the shape, direction and prose of Tolkien's three most famous works: The Hobbit, The Lord of the Rings, and The Silmarillion. Taking the books in chronological order, they lead readers through a strong selection of medieval texts whose echoes can be heard in Tolkien's work, accompanying each extract with an introduction drawing out the influences, comparing the texts and giving some context for the medieval work itself. This is accompanied by an introduction reviewing some aspects of medieval literature, concentrating on those areas which interested Tolkien (Old and Middle English, Old Norse, Gothic, the Kalevala and, to a small extent, Old Irish and Old and Middle Welsh). The introduction also touches on Tolkien's place in Old English scholarship. The interplay of his academic interests with his fiction is presented clearly and with considerable insight (particularly in relation to the Old and Middle English texts). The selection of texts is a good one: many of the most engaging surviving poems and tales are gathered here, in both the original language and in translation. This second edition adds additional Old English texts and the section on the Kalevala, along with short sections in the introduction about literature in Finnish, Gothic, and some of the Celtic languages (mostly Welsh). All of this is useful and likely to be of interest to Tolkien fans and scholars. It also goes some way towards being a reader for those more generally interested in early Northern European literature, in particular poetry.

The problem for me, however, is that to some extent I feel the book falls between two stools. As I mentioned above, I am, in writer-mode, intrigued by the ways in which others write, and their influences. But while the editors here give extracts and parallels laying out the connections they see, these are necessarily outsider views. We do not know, in most cases, how Tolkien saw these texts and their relationship with his fiction, and, while Lee and Solopova frequently give his views as an academic on the early material, they don't and perhaps can't give us this more personal insight. Certainly, authors frequently do not consciously see all their influences, or don't see them in detail, but, at the same time, their own explanations of influence often deviate quite sharply from those of literary critics and not without reason. What we mean to do, what we mean to reflect, what we pastiche or pay homage to, consciously, come from a different place and a different kind of process to unconscious influences, and that can matter.

Steeped as he was in early English and Norse literatures, Tolkien's fiction was perhaps inevitably influenced by them; but it is, I think, possible to overstate this, and, erudite and interesting as it is, this book sometimes verges on this. For instance, "The Ruin" is a splendid Old English poem and I was delighted to see it here as it deserves to be better known, but the parallel the editors draw between it and The Lord of the Rings turns on a sentence—and I fear they may be reaching. The authors suggest "The Ruin" as a source for Legolas's reference to a lost elven city (Fellowship, Bk II, ch. iii) and the memory held in its ruins ("deep they delved us, fair they wrought us, high they built us, but they are gone"); but they cite no real verbal or stylistic overlap. This, then, is a faint connection, in the sense that both are simply a kind of elegy for a former settlement. (I remain very glad "The Ruin" was included, however. It's well worth reading.)

The focus on medieval Northern European literature, moreover, elides the possibility of other kinds of influences: Catholicism, certainly, but also the classics, nineteenth century poets (to me, at least, there are clear echoes of Tennyson in "Nimrodel"), and the wider context of education in literature and culture received by upper-middle-class boys in the early twentieth century. Not all influences are apparent to the writer, and our education shapes how we think, often far more than we realise. The footprints of William Morris' translations of the Norse sagas can be seen in the women of The Lord of The Rings, along with the common imagery of medieval women circulating at that period. This current book is explicitly concerned with early literature, but the question of other, wider influence could perhaps have been raised more clearly.

The writer in me is intrigued by what this book reveals about Tolkien as author. But the other half of me—the academic—has other concerns. Like a number of other mediaevalists, much of my interest in the field was partly triggered by reading Tolkien as a child. But as an undergraduate, his work did not feature greatly on the syllabus I studied and I have reservations about recent moves to widen his role in Anglo-Saxon scholarship. The present book offers a survey of recent work in the field, and cites much of it in the textual notes, but the arguments of Tolkien—often unpublished and taken from his notes or lecture materials—are sometimes given a priority that is potentially misleading. Textual scholarship has moved on considerably since his retirement and this could have been better emphasised. For whatever reason, moreover, Tolkien chose not to publish his views, and, presented in this way, the reader has no way of judging how they may have evolved over time, as no dates are given. Some of the comments are rather basic—we do not gain anything from learning that Tolkien considered F. R. Klaeber's views on "The Fight at Finnsburg" to be "nonsense" (p. 236) without wider context, and this throwaway mention skirts the possibility of some future student accepting the opinion without having the least idea as to Tolkien's grounds for the view.

The texts are well-presented and there are useful introductions to each one, but they are necessarily general and do not present much detail on context or, indeed, on controversies and disputes (for instance the dating of Beowulf, an issue which matters when potential historical elements are mentioned, as here). The matter of transmission is also only lightly touched on: more would be valuable. And source bias is not mentioned at all. This perhaps is a minor matter, but it has significance, particularly in relation to the small number of prose extracts the book contains. Histories and homilies have context and intent and that matters. The presentation of the extract from The Anglo-Saxon Chronicle usually known as "Cynewulf and Cyneheard" omits the question of where, when and why this entry was composed and thus presents without nuance the dominant ninth-century West Saxon narrative of the history of the earlier centuries. And the short section on "Celtic" in the introduction blurs the boundaries between Welsh, Irish and Breton materials, is rather basic in content, and rather tends to fall into the old trap of seeing the Celtic- and Gaelic-speaking peoples as a mono-culture, which they were not.

Again: these all may seem like small things, and in some ways they are. But they go to the heart of my problem with this book. In the end, I'm not entirely sure what it is for. I would not choose to use it as a teaching text for undergraduate students in Old or Middle English (most of the extracts are in these languages), as there is no glossary and no grammatical guide, plus the texts selected are sometimes challenging—there is not enough prose for beginners to work with. On the other hand, as an introduction to the lay reader, some sections are perhaps too technical—the section on Old English verse forms is good, but it is not an easy read for a complete beginner, and, again, the lack of context about the material makes it harder to understand in some ways. The focus on Tolkien forms a theme for the book, but it skews the field: this is, despite its title, not an introduction to medieval literature in general, but to, mainly, Old and Middle English poetry, with some Old Norse Eddic poetry and a few other items. There is no Old French, no Middle Welsh, no Old High German, nothing from Spain or Italy, let alone most of Eastern Europe – or anywhere outside Europe. There is a lot of good material here, and I am always in favour of raising the profile of Old and Middle English and Old Norse. But in the end, it seems the main audience must be assumed to be those interested in Tolkien, whether as fans or as scholars. For students of medieval literature, and for those wanting to explore it the wider field, this is more a companion than a guide.

Kari Sperring is the author of Living with Ghosts (DAW 2009—winner of the 2010 Sydney J Bounds Award, shortlisted for the William L Crawford Award and a Tiptree Award Honour List book) and The Grass King’s Concubine (DAW 2012). As Kari Maund, she’s an academic mediaeval historian, and author of five books on early Welsh, Irish, and Scandinavian history. With Phil Nanson, she is co-author of The Four Musketeers: The True Story of d’Artagnan, Porthos, Aramis and Athos (2005).