The Critical Nexus confronts an important and vexing enigma of early writings on music: why chant, which was understood to be divinely inspired, needed to be altered in order to work within the then-operative modal system. To unravel this mystery, Charles Atkinson creates a broad framework that moves from Greek harmonic theory to the various stages in the transmission of Roman chant, citing numerous music treatises from the sixth to the twelfth century. Out of this examination emerges the centra...