THIS COLLECTION OF ESSAYS from the Fellowship of St. Moses the Black brings forth the old and the new. Some of the material comes from conferences over the decades, and some was commissioned especially for this volume. Themes range from musical history to the unseen spiritual struggle of the liturgical choir. They range from the "sad joyfulness" of the Spirituals-the first music form original to the U.S.-to the creation new Orthodox liturgical music inspired by those Spirituals.