For marketing purposes, record companies often use “Adagio” to mean any slow piece with a strong emotional content.

“Adagio,” however, means “to go at a slow or easy pace”—and it’s that pace, characterized by an insistent, underlying pulse, that allows for both peaks and valleys of emotion. 

In this hour, how a simple tempo notation makes for memorable music by Albinoni, Mozart, Beethoven, Tchaikovsky, Khachaturian, Rodrigo and Barber.