Difference is existence. Without difference, there is nothing, in that there is unity, in that there is indistinguishability, in that there is nothing. Difference is necessary for existence, even if only difference in time. Say there is just one thing – this will not hold true if there is not change, if this thing is not somehow distinguishable at one moment from another, for how else would it exist? How else could it be distinguished from non-existence, if there is no difference in time to establish it? But time is not enough. One unchangeable thing cannot exist even in time, for time is difference and if there is no difference, there is no time. But the difference must come in the thing that exists, not just in time -- for what would that mean? -- such that the thing is at one point distinguishable from the way it is or was at some other point. Otherwise, there is nothing to distinguish, and there is nothing. So there must be change, or difference, for there to be anything.
Still more, we need difference between one thing and another. We need a multiplicity of things, or differences, in order for there to be existence at all. If we say that only one thing exists, proven by something changing from one moment to another, then this thing will only exist insofar as it is not quite the same thing as it was before, and thus there are two things. This is then what exists – the difference. At any one time, existence exists only in difference, and so there must be difference between things. That is what exists. Imagine a plain white canvas with one red dot in the upper right corner. Imagine this is all there is. What exists? Difference. The red exists, but it exists only insofar as it is different from the white around it. The same with its shape. Its round dot shape exists only insofar as it demarcates one precise way in which it differs from the difference that surrounds it, that is, from the white. Even its location, being in a particular spot on the white canvas, exists only in that it differs from the location of all else. This is what gives it its place -- difference.