 The Puzzle of Dion and Theon. The Stoic philosopher Chrysippus asks us to consider the case of Dion and Theon, where Dion is a normal human being and Theon is a large part of Dion consisting of everything but Dion’s right foot. Suppose now that the right foot is removed. Theon obviously survives the operation, for his parts remain completely unchanged. But, in that case, it seems as if Dion does not survive the operation, for otherwise we would have two people in the same place at the same time. Hence, Dion does not survive the loss of his foot. More generally, the argument would show that material objects cannot survive the loss of any constituent parts. (A modern version of the puzzle, due to Peter Geach, concerns Tibbles and Tib, where Tibbles is a cat and Tib a cat-part consisting of everything but Tibbles’s tail.)