 Identity through time generates a number of problems posed by puzzle cases such as the case of Cup and Tcup. Later we will review a number of solutions to those problems offered in the literature. One problem about identity through time is not raised by consideration of puzzle cases. It arises simply because persisting things can change their intrinsic properties. For that reason it has been labeled by David Lewis the problem of temporary intrinsics (Lewis 1986, 202–205).