On page 123, "I remember the stage manager of Tommy on Broadway boasting that the pacing of the show was so stable (i.e., the music was performed to a “click” track) that the running time of each performance was within 30 seconds every evening!" What was actually so remarkable about the stage manager's claim was that each performance was within thirty seconds even though the music was NOT performed to a "click" track .

https://blog.preludemusicplanner.org/2012/07/tactus-and-tempo

http://discovermagazine.com/2010/sep/25-modern-humans-smart-why-brain-shrinking