 There may seem to be another obstacle to accepting Stein’s relation \(R\) as representing a genuine relation of becoming. \(R\) is supposed to represent becoming, but the light cone structure of Minkowski spacetime, in terms of which it is defined, is inert. This reaction was voiced, for instance, by Palle Yourgrau, who wrote that “Stein’s mistake is to adduce a structural property as what ‘justifies the use of our notion of ”becoming“ in relativistic spacetime.”’ (1999, p. 77) If Yourgrau has put his finger on a “mistake”, then it is a “mistake” at the very heart of Stein’s effort. There are, however, a few remarks to be made on this score.