Exodus 11:5

5. And all the firstborn in the land of Egypt shall die Israel consecrated all its firstborn to God, and Egypt’s firstborn were taken in wrath, as were Israel’s in mercy . The firstborn is the flower, the glory, of the nation, and thus the choice victims were taken from all ranks of men and from all kinds of beasts . The maidservant that is behind the mill, behind the two millstones . Here the specified ranks are from the king to the maidservant, and in Exodus 12:29, from the king to the captive .

The handmill in common use in Egypt, as in the East, generally consists now, as then, of two round stones, from one and a half to two feet in diameter, the lower one being convex upon its upper surface, which fits into a corresponding concavity in the upper stone. The corn is dropped through a hole in the upper stone, which is revolved by means of an upright handle. It is usually worked by two women sitting on the ground, facing each other, with the mill between them, both holding the handle and pushing and pulling in alternation. See illustration at Matthew 24:41. The Egyptians had also larger mills worked by asses or cattle .