This is the book, or a fragment of the book, that R. G. Collingwood was preparing to write his entire life. It is, in this edition, very incomplete. I have rated it as four stars only because there is too much matter from the editor, and not enough of Collingwood. This book, read in conjunction with his series on Philosophy and History, particularly the "Essay on Metaphysics", "The Idea of History", and "An Essay on Philosophical Method", will give the reader a very complete idea of Collingwood's philosophy. The book, as Collingwood conceived it, but did not live to complete, was to be an expanded version of his earlier "Speculum Mentis" (1924), which was his only complete treatise covering the entire range of philosophy.
"Speculum Mentis" is in fact one of the most remarkable books written in the last century, and Collingwood must be rated among the great philosophical thinkers of all time. Like all the great philosophers he has been misunderstood, most of all by philosophers, who, rather than read the text read their own interpetations into it, and then try to classify and pigeonhole the writer based on this. His writing style is beautiful. He is nearly as easy to read as C. S. Lewis, whom he knew, and more so than his close friend and colleague at Oxford, the Celtic philologist, J. R. R. Tolkein.
The best book covering these three and their teachers at Oxford is James Patrick, "The Magdalen Metaphysicals: Idealism & Orthodoxy at Oxford, 1901-1945"(Mercer University Press, 1895), which is available through Amazon.com. This interesting book should lead you to a new understanding of these men and the similar philosophy that informs the work of each.