According to Peter Ludlow, there is a very close relation between the structure of natural language and that of reality, and one can gain insights into long-standing metaphysical questions by studying the semantics of natural language. In this book Ludlow uses the metaphysics of time as a case study and focuses on the dispute between A-theorists and B-theorists about the nature of time. According to B-theorists, there is no genuine change, but a permanent sequence of events ordered by an earlier-than/later-than relation. According to the version of the A-theory adopted by Ludlow (a position sometimes called "presentism"), there are no past or future events or times; what makes something past or future is how the world stands right now.