 Stage theory enjoys the following advantage over classical four-dimensionalism. Consider the case of a person fissioning into two later people. A classical four-dimensionalist like Lewis will say that before the fission there are two separate people that cannot be told apart. The stage theorist has no need to say that. Instead the stage theorist can say there is a single present person who will be identical with each of a pair of later individuals in virtue of standing in the relevant counterpart relations to each one.