One of the repeated themes of the Exodus narrative is the phenomenon of Pharaoh’s “hardened heart”, initially self-generated, later with assistance from God.
This ability to remain unsympathetic to the plight of the Jews who wished to leave, and to the suffering of his subjects, enabled Pharaoh to withstand the unrelenting pressure of the havoc-wreaking plagues.
The externally enabled inflexibility puzzles all the commentators, who cannot fathom how someone deserves punishment if his resistance to pressure is unnatural. How can Pharaoh be blamed, and therefore be forced to suffer the consequences of his stubbornness?
Rabbi Dunner explains the background to Pharaoh’s superhuman ability to withstand Moses’ warnings, and offers a variety of explanations for this strange aspect of the Exodus story.