McGuire’s ‘Source: Reflections on Neil Gunn’s novel Highland River’ is a key work in the composer’s output, bringing together various strands of his characteristic working methods and embodying a distinctive approach to formal development. The author seeks to locate the work with reference to some characteristics of Celtic culture and to aspects of 20th century modernism in music, but also employs Hugh MacDiarmid’s poem ‘By Wauchopside’ in an investigation of the psychological, developmental and aesthetic implications of the musical work