Loreena McKennitt's songs unfurl like medieval tapestry, revealing vibrant color and mystical detail that seem beyond the capacity of earthly mortals. The Canadian singer can hold a note as long as anybody, and on "The Mystic's Dream" (1996) she draws out a heavenly vibrato over a track that rumbles like the end of the world: Celtic and Moroccan instruments weave a dense web of sound over baritone Gregorian-style chants. These fusions are her forte. "The Gates of Istanbul," for instance, from 2006, dances over a tight, syncopated beat while lyrics portray music itself as a cosmic North Star.