The Allegory of Love … is a work which has all the authority of a mind of the highest quality marking out clear paths in a complex and absorbing mass of material. As such it effortlessly joins company with that very small class of books for which a future can be confidently predicted. They are those works which handle a large subject—large not in range, merely, but in significance to the human spirit—with a pioneer’s skill, marking out new country and leaving an indelible impression for all subsequent settlement of the area. They can be wrongheaded in approach or mistaken in detail; but they must not be so much accounts of literature in the past as themselves instances of literature in being.
When Anatole France spoke of literary criticism as recording the adventures of the soul among masterpieces he doubtless had something of the sort in mind. Alas! from the ordinary output of criticism we can only conclude that there are some very dull souls about. Yet there is a rare category of works of criticism that justifies the aphorism. One thinks of Bradley’s Shakespearian Tragedy, Ker’s Epic and Romance, John Livingston Lowe’s Road to Xanadu, to name no others. Each is a book which not only shows great powers of penetration and organizing skill; each succeeds in communicating the activity of a mind of the highest quality entirely intent on the material before it, to which it is giving new and distinctive shape. Let us describe these books in one word: they are in the highest degree readable.
Lewis’s The Allegory of Love surely belongs in any such classification. There is a luminous intelligence of the first order at work—an angel who writes as only Lewis could, humorously, graphically, and with an exalted seriousness. To be sure, there are things to be disputed, in Lewis’s book as in all the others of its distinguished class. Lewis was the first to point them out…. But, as with the other works I have listed, here is a book, obedient to the first rule of writing—that on every page it asks to be read. How many extended works of literary criticism are truly unputdownable? It is the severest test; and The Allegory of Love triumphantly survives it.
From John Lawlor, C.S. Lewis: Memories and Reflections (1998). Prof. Lawlor was an undergraduate student of Lewis’ and a graduate student of J.R.R. Tolkien. This review was written near the end of his life, on the 100th anniversary of C.S. Lewis’ birth. It begins a section that describes the strengths of The Allegory of Love in detail, and puts it in the context of Lewis as a scholar who was writer worth reading. You can see my full review here. The italics in the text are original, but I added the bold highlighting and changed the paragraphing a little.