Integrated Bounds
Every thing has its own space — although there is only one space, space, for it is endless. Everything that exists is part of it, a thing in it.
Things may sometimes be regarded as the opposite of space — since space is open and boundless, while the things are rather bounded and closed. As such they separate a region of space. And that is exactly how, after all, space is somehow bounded: by the things. Through them it can be left — and another one can be entered.
It is the space of the thing, that is entered in this way. But, once entered, the space that initially appears to be the closed interior of the thing turns out to be space itself, the endless one, the universe. Because from inside no bounds are to be recognized.
So, where do they go? — Well, quite simply: again they are incorporated in the things of (this) space; and so they are perfectly integrated, yes, they are the ultimate substance of space.