One day near the end of his life, Paul Erdos observed that the audiences at his lectures had been getting larger and larger, to the point where they filled halls so large that his old and feeble voice could hardly be heard.

Erdos produced a theory to account for his growing popularity: "I think," he explained, "it must be that everyone wants to be able to say 'I remember Erdos; why, I even attended his last lecture!'"

[Erdos often joked about the fact that, over the course of his lifetime, the estimated age of the Earth had grown from two billion to some 4.5 billion years, making him "two and a half billion years old"!]