Hermeticist Fabre d'Olivet's classic study of music as sacred art and its profound effects on the soul. Ever since Pythagoras demonstrated the mathematical basis of music and its profound effect on the soul, the Western esoteric tradition has been deeply involved with the science and art of tone. Fabre d'Olivet (1767-1825) was the first to restate Pythagoras' ideas in modern terms, and to show the way for music to regain its spiritual heritage. He calls for a complete reevaluation of its nature and purpose. Fearless in his criticism of the trivialization of music in his own time, d'Olivet recalls its ancient glory in China, Egypt, and Greece. He shows that music is rooted in the same principles as the universe itself, and that it is intimately connected with the destiny of mankind. 
New edition of Music Explained as Science and Art.
A man of astonishing insights and strange revelations, Fabre d'Olivet is increasingly recognized as an essential link in the golden chain of Western theosophy, and as a prophetic figure with a message for our own age. 
Antoine Fabre d'Olivet (December 8, 1767, Ganges, Hérault – March 25, 1825, Paris) was a French author, poet and composer whose Biblical and philosophical hermeneutics influenced many occultists, such as Eliphas Lévi, Gérard Encausse - Papus and Édouard Schuré.
His best known works are on the research of the Hebrew language and the history of the human race entitled The Hebraic Tongue Restored: And the True Meaning of the Hebrew Words Re-Established and Proved by their Radical Analysis, and Hermeneutic Interpretation of the Origin of the Social State of Man and of the Destiny of the Adamic Race. Other works of renown are on the sacred art of music entitled Music Explained as Science and as Art and Considered in its Analog Relationship with Religious Mysteries, Ancient Mythology and the History of the Earth, and a translation and commentary of Pythagoras's thirty-six Golden Verses.
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.