 One could also allow a present that corresponds to some small length of time that humans typically think of as the present—an interval that may range from about .5 seconds to 3 or perhaps 4 seconds. This is the time it takes to read a sentence or hear a musical phrase and is sometimes referred to as the specious present. If we let T indicate the length of a specious present and we try to follow Stein’s injunction to define notions in terms of intrinsic structure, then Arthur (2006) and Savitt (2009) have suggested that the present for a stretch of worldline or process of length T would be the region of spacetime comprised of the intersection of the future light cone of the point at the beginning of that process and the past light cone of the point at the end of it (assuming the process is or occupies a closed interval). This region is often called a causal diamond. (See Winnie (1977) for more on causal diamonds.)