Isidore of Seville : After these plagues came rotten and swollen cysts, along with fever, as the sixth plague. In the ulcers the troubled and purulent evil of this age is signified; in the cysts swollen and inflated pride; in the fevers anger and the madness of rage. Up to this point such punishments as were inflicted on the world were tempered, insofar as its errors were represented by signs. Questions on the Old Testament, Exodus