In eighteenth-century Germany the universal harmony of God's creation and the perfection of its proportions still held philosophical, moral and devotional significance. Reproducing proportions close to the unity (1:1) across compositions could render them beautiful, perfect and even eternal. Using the principles of her groundbreaking theory of proportional parallelism and the latest source study research, Ruth Tatlow reveals how Bach used the number of bars to create numerical perfection across his published collections, and explains why he did so. The first part of the book illustrates the wide-ranging application of belief in the unity, showing how planning a well-proportioned structure was a normal compositional procedure in Bach's time. In the second part Tatlow presents practical demonstrations of this in Bach's works, illustrating the layers of proportion that appear within a movement, a work, between two works in a collection, across a collection and between collections.

Winner, 2016 Choice Outstanding Academic Title

'[This book] takes in all Bach’s major collections and more, including the two Passions, three Oratorios and the B minor Mass. In sheer extent and richness of background, and number of works examined, Tatlow’s book is a most original and impressive achievement that will need to be taken into account in future discussions of these fascinating compositions.'

David Ledbetter Source: Early Music

'For anyone who wishes to explore the logical pathways of Bach's genius, Tatlow's analysis gets to the heart of the aesthetic, theological and Pythagorean presuppositions underlying the Bachian concepts of 'Vollkommenheit', perfection through calculation; and 'Harmonie' … the harmony of proportion, here a mirror of divine order.'

Gian Mario Benzing Source: translated from Corriere della Sera (La Lettura)

'… Tatlow’s approach to the subject matter is unique, and the vigorousness with which her methodology is applied has uncovered numerous new and unexpected facts. Bach scholarship cannot ignore her voice.'

Yo Tomita Source: Music and Letters

… Bach’s Numbers clears the way for some promising new directions in Bach scholarship. Tatlow’s work should be valued not only for what it suggests for future study, however, but for what it provides in its own right: a bold historical rendering of Bach’s compositional process that forces us to view some of the composer’s greatest works in a new light, and with deepened appreciation.'

Robert L. Wells Source: Music Analysis