The second sentence, "The dust of the earth falls on the world itself," unites the the falling of the dust as an actual experience with the idea of it as a universal principle, true for all places at all times. It has a dual purpose. Its first role is like that of a conclusion to a piece of writing, perhaps, where the writer (me?) is trying to sum up some phenomenon that he has experienced.
In this case, it would be as if he had plucked a line from a poem or a piece of literature. This is a distinct possibility, though I have no conscious recollection of doing so. As I said, the sentence somehow popped into my head. We will continue this detective game later.
Here, again, we come back to the possibility of metaphor.
The other implication of the sentence is that it is some sort of universal decry, a principle of the world's dust, always to fall upon itself, in the past, in the future. But what of now? If we are to unite its optioned metaphorical function, as a line of a poem grasped at to describe some phenomenon, with the implied universalism, then we get something very strange indeed. We get the certainty of the world's dust falling upon itself, but only with the possibility of it falling in the past and in the future. To put it another way, it has only the possibility of falling in the past or the future because it cannot be falling as such in the present. That is the nature of metaphor; never actual, but almost actual.
What we find is a present devoid of this falling dust. We find a present with a certain sense that this event happens; that this event happens always; that it happened; that it will happen again. But the vague universalism of the metaphor imbues it with uncertainty. The question then becomes, "It may be happening now, it may have happened, and it may happen again, but will it be the same every time it happens?"
Metaphor robs the truth, robs those stone bare fact, robs non-speech and non-language, robs silence from its own silence, robs the silence of the world from itself. It must do, to function as metaphor.
Where does it put this silence, if we are to take the idea of stealing or robbing seriously? Where does it hide it? Within itself, perhaps, behind its own back, maybe.