Regarding thinking along the lines of atoms and void for the desires, I too was starting to go in that direction but I don't think that it's fruitful. It could easily lead to thinking that an urge or thought comes from the void, which opens the door to the supernatural.
I'm pretty certain that none of us are thinking of anything coming from the void: we all agree (right?) that everything, including desires and thoughts, are ultimately material. But I can envision all sorts of people latching on to the idea that various things come from the void. Well, I don't even have to envision it as all sorts of people already think that various things (gods, angels and all types of woo-woo) come from the void!
Referring to desires or thoughts as "empty" is completely different from relating them to the void, despite any linguistic similarity. At least as far as I can tell.