The first angel of the ‘Daughters of Music’ is ‘Rhythm’.  Music maintains an underlying unit of time commonly known as the beat.  The tempo to which listeners follow by tapping their foot or dancing to the beat of the music.  Other terms that refer to rhythm are meter, groove and syncopation.

The rhythm of European music written before the 20th century typically had a fixed syncopation – a fixed and easily discernible pattern of strong and weak beats. 

At the dawn of the of 20th century a new form of rhythm emerged, a sole American invention, that killed fixed syncopation – ragtime and later jazz (then later 'swing').   Innovative musicians altered music’s syncopation and made it ‘ragged’ – the ragtime rhythm. 

Jazz, with its blue notes and improvisational rhythm, became the soundtrack to the modern world (Einstein’s space-time relativity to Picasso’s art) .  It is an art form that symbolizes the American spirit and idealism:  freedom and individual expression with selfless collaboration. 

Much of today’s popular music has what’s called the backbeat, where accentuation is on the ‘off’ beat of the rhythm.  The backbeat defined Rhythm and Blues (R&B) and became one of the defining characteristics of rock and roll and contemporary music.