Without the efforts of Belle Stewart (born: Belle Perthshire), many of Scotland's traditional folk songs and stories would have been lost. Taught her father's repertoire by her brothers, Donald and Andy, she became a national treasure. Her albums -- including The Stewarts of Blair, released in 1965, and Queen Among the Heather: Scots Traditional Songs and Ballads, released 11 years later -- introduced many listeners to Scotland's musical past. The daughter of traveling folk, a caste of nomadic craftsmen whose descendants made weapons and ornamentation for the ancient clans of the Highlands, Stewart became the pallbearer for the caste's oral traditions. Her father, Donald "Dan" MacGregor, a tinsmith, fisherman, and amateur ballad singer, died when she was seven months old. In order to keep the family together, her mother gave up the nomadic life and settled into a home in Blairgowrie. Outside of accompanying her husband, Alec Stewart, whom she married in 1925, on periodic forays to his ancestral home in Ireland, Stewart traveled very little. During their first trip in the early '20s, she learned that many of her husband's relatives were pipers, dancers, singers, and storytellers. His father was, in fact, a national champion piper. Stewart first came to the attention of folklorists in the mid-'60s when Hamish Henderson, a folk music collector for the School of Scottish Studies, came to Blairgowrie seeking someone who knew the old folksong, "The Berryfields of Blair." Directed to Stewart, Henderson hit the mother lode. Not only did she know the song, she possessed an extremely vast repertoire of traditional folksongs and ballads and originals that she had written for weddings and other occasions. Henderson was so impressed that he booked time in the studio at the School...