  At the opposite extreme to the 4-D Block view is Presentism, the doctrine that concrete reality is confined to the momentary present. Presentists deny any reality to the past or future. Coming in between these extremes is the Growing Block model. According to the latter, the past is real but the future is not, and the sum total of reality is gradually increasing, by a process of moment-by-moment ‘absolute becoming’. On this view the present is merely the most recent addition to reality; it is also the interface between being and non-being. The Moving Spotlight model is in one respect akin to the standard Block model: it accords reality to all times and events, including those yet to occur. It differs from the latter by virtue of the fact that it incorporates objective passage into the universe, in the shape of a privileged (and constantly advancing) present – indicated by the blue line in Figure 20. Moving Spotlight theorists agree with Block theorists that both the future and the past exist, but they tend to hold that present events are (in some manner)  distinctive.[25]