Carl Sagan's Encounter With a Dolphin's Theory of Mind

I was swimming in a large indoor pool with Peter. When I threw the pool's rubber ball to Peter (as was natural for me to have done), he dove under the ball as it hit the water and batted it with his snout accurately into my hands. After a few throws and precision returns, Peter's returns became increasingly inaccurate – forcing me to swim first to one side of the pool and then to the other in order to retrieve the ball. Eventually, it became clear that Peter chose not to place the ball with...