Heard this on the radio this morning, and thought it was worth sharing. It's one of the more interesting scenes in opera, the prologue to Pagliacci, which generally takes place in front of a curtain prior to the start of Act 1, directly addressing the audience. His theme, which is the moral of the story we are about to see, is that "actors have feelings, too." When it's done well it's a real show-stopper, and the applause it garners can be greater even than that for the opera's most famous aria, Vesti la giubba.
Here's the great Sherrill Milnes in a concert performance.