Avery interesting book about unknown aspects of music. I particularly like this: "Music is not merely, as is imagined today, the art of combining tones or the talent of reproducing them in the way most pleasant to the ear: that is the practical side from which result the ephemeral forms... Music regarded in its speculative aspect is, as the Ancients define it, the knowledge of the order of all things, the science of the harmonic relationships of the universe; it rests on immovable principles which nothing can alter." I highly recommend this book.