According to Presentism, time is an ordering of various realities. At a certain time some things exist and others do not. This is the only reality we can deal with and we cannot for example say that Homer exists because at the present time he does not. An Eternalist, on the other hand, holds that time is a dimension of reality on a par with the three spatial dimensions, and hence that all things—past, present, and future—can be said to be just as real as things in the present. According to this theory, then, Homer really does exist, though we must still use special language when talking about somebody who exists at a distant time—just as we would use special language when talking about something far away (the very words near, far, above, below, and such are directly comparable to phrases such as in the past, a minute ago, and so on).

According to what theory is time an ordering of various realities?