""Gregorian Accompaniment: A Theoretical and Practical Treatise Upon the Accompaniment of Plainsong"" is a book authored by Louis Niedermeyer and published in 1905. The book delves into the art of accompanying Gregorian chant, which is the traditional plainchant used in the Roman Catholic Church. The book provides a theoretical and practical guide to the accompaniment of plainsong, including the use of harmonies, counterpoint, and other musical techniques. Niedermeyer, a renowned composer and music educator, draws on his extensive knowledge of music theory and composition to provide a comprehensive overview of the subject.The book is divided into several chapters, each of which covers a different aspect of Gregorian accompaniment. Topics covered include the history of Gregorian chant, the principles of Gregorian accompaniment, the use of different instruments in accompaniment, and the role of the accompanist in enhancing the beauty of the chant.The book is written in a clear and concise style, making it accessible to both scholars and practitioners of Gregorian chant. It is considered a seminal work in the field of Gregorian accompaniment and is still widely used as a reference by musicians and music educators today.This scarce antiquarian book is a facsimile reprint of the old original and may contain some imperfections such as library marks and notations. Because we believe this work is culturally important, we have made it available as part of our commitment for protecting, preserving, and promoting the world's literature in affordable, high quality, modern editions, that are true to their original work.