5 And all the firstborn in the land of Egypt shall die, from the firstborn of Pharaoh that sitteth upon his throne, even unto the firstborn of the maidservant that is behind the mill; and all the firstborn of beasts.
Finally the firstborn of the Egyptians are destroyed. They are the principalities and powers and the rulers of this world of darkness. Or they are the originators and inventors of the false religions that existed in this world. The truth of Christ put an end to these religions and wiped them out, along with their inventors.
[AD 636] Isidore of Seville on Exodus 11:5