There are about 140 people in a large room. In the center of the room is a piano.
Philip Glass walks to the center of the room. He talks to the audience about music.
Philip Glass stops talking about music. He sits at the piano.
Philip Glass plays the piano.
Many of the people in the audience listen.
One man in the front row realises the seat to his left is empty. He looks at this empty seat with concern. This is the seat that his wife is supposed to sit at. But she is not there. The man is wondering why she is not sitting in this seat. Regardless, he places his program on the seat.
Philip Glass takes no notice, because he is preoccupied with playing the music correctly.