Actually, in the history of music, rhythm changes inside a phrase are not that old. Hugo Riemann coined the phrase Agogik (Agogics) in 1884 and the following things were included:
- accel. (accelerando) – accellerate - play increasingly faster
- string. (stringendo) – more hurried
- ritard. or rit. (ritardando) – slow down
- rall. (rallentando) – gradually slow down
- smorz. (smorzando) – ersterbend
- più (or meno) mosso – with more motion (or less)
Additional qualifiers: poco (‚a little‘), poco a poco (‚gradually‘), or ma non troppo (‚not too much‘)
Much earlier, sudden pauses were used to simulate an accent with instruments like the organ or harpsichord that had little possibilities with this type of more pronounced articulation. This is not to say that agogics were not performed before 1884, rather that the music world felt a need to describe the phenomena.
In audio playback, we hopefully have the "organic" recording where agogics are applied tastefully, and we have the level that keeps the phrase "connected" in spite of the additional length or space. Exaggerated articulation can destroy the feeling that notes belong to one another.
Whenever I feel blue, I start breathing again.