Since the l6th century, to have the blue devils,
or to be blue
has referred to a fit of melancholy. Then, around 1900 the term was adopted by players of a style of African-American folk music that expressed just such a mental state. A typical early
blues
song is characterised by a repeated musical sequence of three chords played over 12 bars, with a three-line structure to the lyrics consisting of a repeated line and a rhyming refrain. The instruments...