All across the southern American Black Belt, that arc of dark black upland soil where the short staple cotton grows so profitably, there are still plenty of modern day plantations with modern day massas and field hands and that makes it as good a place as any to define what Pure Modernity did and didn't mean by 'dirty'.
If you grow up out in the country (anywhere ,not just in the Black belt) you know that 'clean fill' just means dirt (soil) free of too much in the way of industrial pollution.
The term is usually seen on a sign stuck up on a low-lying piece of cheap land that the owner wants filled up to the average level of the surrounding area, so that eventually it will get county approval for a house and a septic system on it.
The idea is that dump truck drivers are paid by the load to haul away soil excavated from a construction site and the shorter distance the driver has to go to get rid of the stuff, the more money they make in a day.
The landowner planning to fill up his low lying wetlands is really seeking 'free clean fill' and they usually get it, because if the dump trucker must normally drive twenty miles to get rid of the load at a municipal waste site and also pay a tippage fee to do so, dropping it off a mile or two away for free is a no-brainer.
All this to say that even pure black dirt, as black as the field hands that tend it, can still be 'clean' and 'pure' - if left out in the field.
As clean and pure as the pure white bed sheets inside the massas' bedroom, sheets as white as the massas himself and his spouse.
Both black dirt and white sheets are equally clean and pure, as long as they remain in their separate spheres : separate and equal.
But if even the smallest possible amount of that black dirt from the field gets left on those white sheets, perhaps from the field hands' feet, then the sheet is now 'dirty'.
Very very dirty : dirty as in Mandingo 'dirty' miscegenation.
To Pure Modernity, 'dirty' was just about anything, 'out of order'.
Because under Pure Modernity the key base assumption about reality was that it was indeed 'ordered' , even if the order was buried deep down inside the structure of reality and not easily seen or even yet detected by the best scientific instruments.
If you hold the opposing (and more current) view of reality, that everything in reality seems either already intertwined or potentially able to intertwine, you might suspect big problems for people living in the era of Pure Modernity.
That is because while they claim there is deep hidden clean purity and order everywhere, on the surface everything seems intertwined, IE dirty.
The social history of Pure Modernity then seems to threaten a repeat of that tale of frantic people with brooms running around wildly, trying to hold back the tide.
And I think that is what you indeed do find : an endless series of moral panics all revolving around fears of two supposedly separate spheres (say Jew and Aryan) touching and interacting...