This is a metaphor, it seems likely, with Christian roots.
It occurred to me to comment the other day that even though Jesus often spoke of the Shepherd guiding his flock, the fate of the flock–particularly for Middle Eastern sheep, although I am not finding easy details with a basic internet search–was murder by the Shepherd, and being carved up for meat. It seems likely that wool was a product more practical for sheep raised in much colder climates, like Britain and Scotland.
We have a local Middle Eastern shop (quite a few actually, but this is the closest one to me). They have Lebanese flags everywhere, but say they are Palestinian. A couple months ago, they had a sheep carcass on the floor when I went to buy whatever it was, usually bulgur wheat, zaatar, sumac, and sometimes their yogurt and interesting cheeses. I make my own lebneh. It had been skinned, but was otherwise intact. I was with my oldest, who is a vegetarian, and did not mention it until after we left. Just laying there in plastic on the floor. I think the older brother likely got it there himself. Halal slaughter, no doubt.
Mutton and veal are both produced, ultimately, by the work of shepherds, and sheep dogs. “Sheep to the slaughter” is of course an old metaphor.
I have no particular agenda, commenting on this, other than to point out how often we fail to see obvious problems with metaphors we use. I still like the metaphor–I think it comes from David Grossman–but wanted to complete it.
I’m that guy. Sometimes. Many people call us assholes.