Prelude to the Metaphysics of Ping-Pong

One summer the philosopher of science Rupert Sheldrake and his family paid us a visit. I gave the two boys rackets: they were hooked. They now have a table of their own. Whenever we visit, we play for hours. Eventually, we realized what was intriguing us: the fact that ping-pong is
strikingly non-Euclidean.