Einstein, Casals, Picasso, and George W. Bush die and go to heaven.

Einstein, Casals, Picasso, and George W. Bush die and go to heaven. St. Peter is waiting for them, and requests identification. Einstein, who is first in line, says "I don't have any ID, but I can explain the equivalence of matter and energy." He is given a blackboard and proceeds to give an eloquent explanation of one of his most famous theories.
"Only Einstein himself could explain this so well," says St. Peter.
"Step right in, professor. Next?"
Then Casals, who is next in line, says "I don't have any ID, but I can
play my cello to prove who I am." He is given a cello and plays the most beautiful music imaginable.
"There's no question, you must be Casals," says St. Peter. "Next?"
Picasso steps to the gate. "I don't have any ID, but I can paint a
picture to prove who I am." He is given some brushes and paints a spectacular picture.
"Okay, you're Picasso. Go right ahead," says St. Peter. "Next?"
"I'm George W. Bush," says the former president, "but I don't have any
ID. How can I prove who I am?"
"Well," says St. Peter. "Einstein was just here, and he discussed some
of this theories. Then there was Casals , who played the cello for us. Then Picasso came, and he painted a picture. Can you do anything like that?"
"Who are Einstein, Casals, and Picasso?" asks Mr. Bush. St. Peter
looks at him and says,"Mr. President, go right in."