A lot of traditional music, especially Scottish and Irish is termed 'Modal' because it doesn't follow the conventional modern major or minor scales. One such mode is the Lydian, whose scale runs from F to F on the white notes of the piano. This gives the scale a brighter sound than the modern Major scale.
Modes and Scales can be traced back to Greek origins, where different tribes evolved different scales. The scales ran down from a tonic note (rather than up which is the modern method) and maintained certain intervals between notes. The Greek scales (and medieval modes) used only the natural notes (no sharps or flats) which are equivalent to the white notes of a piano. This gives a characteristic interval between notes in the scale.
Apparently "the Lydian mode is often used by soundtrack composers to depict and describe the feelings of a child who discovers the world with wide-open eyes, mixing playfulness and excitement along with cheerfulness and awe."!
The Hutchinson Encyclopedia gives this alternative definition of Lydian, parts of which some of the choir may be happy to be associated with!
