"Canto Gregoriana", a collection of recordings of Spanish monks singing Gregorian chant, has appeared in the pop-music charts. This companion volume discusses why this music has such a calming effect on both singers and listeners, how it is sung, and how it originated and developed. The author traces the history of Gregorian chant from the founding of the Benedictine Order in Italy in the 6th century to the present, and shows how, from the days of early Christianity, liturgical singing has been used as a spiritual exercise. She explains the construction of the chant and the techniques that must be employed to sing it properly, and explores the effect of these simple, pure, unaccompanied tones on the body, mind and heart, as she describes recent research on the therapeutic power of the human voice and its ability to transform consciousness. The appeal of Gregorian chant seems to lie in its mystical minimalism, its spare rhythmical settings, and its promise of peace. This book discusses how it continues to have appeal and meaning today.