standing in a certain order which McTaggart chooses to call the A-series and the B-series. The A-series represents the series of positions determined as future, present, and past, and which continuously pass from the distant future towards the present, and through the present into the remote past. The B-series represents the series of positions determined as earlier than or later than each other. The determinations of the B-series hold between the events in time, and never change. If an event ever is earlier or later than some other event, then their respective position in time never changes. The determinations of the A-series must hold to something outside of time, something that does not itself change its position in time, but in relation to which the events in time pass from being future, present, and past. Surprisingly, McTaggart does not suggest the present, or NOW, as this something whose position in time is fixed and unchanging. He just says that it will be difficult to identify any such entity (seeing as it is outside time). Broad explains that McTaggart believed that the difficulty of identifying this entity was serious enough in its own right to be persuaded that time is unreal, but thinks that the contradiction of the A-series is still more convincing; for that reason he leaves this particular difficulty aside. The atemporality of the B-series McTaggart argues that the conception of time as only forming a B-series is inadequate because the B-series does not change, and change is of the essence of time. If any conception of reality represents it as changeless, then this is a conception of an atemporal reality. The B-series does not change because earlier-later relationships never change (e.g. the year 2010 is always later than 2000). The events that form a B-series must therefore also form an A-series in order to count as being in time, i.e. they must pass from future to present, and from present to past, in order to change. The A- and B-series are not mutually exclusive. If events form an A-series they automatically also form a B-series (anything in the present is earlier than anything in the future, and later than everything past). The question is not therefore whether time forms an A- or a B-series; the question is whether time forms both an A- and a B-series, or only a B-series. The proponents of the B-view of time typically