Mayonnaise jar– the story of life

A FRIEND e-mailed me the following story recently. The title of the story is A Mayonnaise Jar and 2 Cups of Coffee. The story goes like this: 

A professor stood before his philosophy class and had some items in front of him. When the class began, he picked up a large and empty mayonnaise jar and proceeded to fill it with golf balls. He then asked the students if the jar was full. They agreed that it was.