After the plague of blood "Pharaoh's heart was strong" ("hardened"), and this is distinctly ascribed to his own action, because "he set his heart even to this" (vii. 22, 23).
After the second plague, it was still he himself who "made his heart heavy" (viii. 15).
After the third plague the magicians warned him that the very finger of some god was upon him indeed: their rivalry, which hitherto might have been somewhat of a palliation for his obstinacy, was now ended; but yet "his heart was strong" (viii. 19).
Again, after the fourth plague he "made his heart heavy"; and it "was heavy" after the fifth plague, (viii. 32, ix. 7).
Only thenceforward comes the judicial infatuation upon him who has resolutely infatuated himself hitherto.
But when five warnings and penalties have spent their force in vain, when personal agony is inflicted in the plague of boils, and the magicians in particular cannot stand before him through their pain, would it have been proof of virtuous contrition if he had yielded then? If he had needed evidence, it was given to him long before. Submission now would have meant prudence, not penitence; and it was against prudence, not penitence, that he was hardened. Because he had resisted evidence, experience, and even the testimony of his own magicians, he was therefore stiffened against the grudging and unworthy concessions which must otherwise have been wrested from him, as a wild beast will turn and fly from fire. He was henceforth himself to become an evidence and a portent; and so "The Lord made strong the heart of Pharaoh, and he hearkened not unto them" (ix. 12). It was an awful doom, but it is not open to the attacks so often made upon it. It only means that for him the last five plagues were not disciplinary, but wholly penal.
Nay, it stops short of asserting even this: they might still have appealed to his reason; they were only not allowed to crush him by the agency of terror. Not once is it asserted that God hardened his heart against any nobler impulse than alarm, and desire to evade danger and death. We see clearly this meaning in the phrase, when it is applied to his army entering the Red Sea: "I will make strong the hearts of the Egyptians, and they shall go in" (xiv. 17). It needed no greater moral turpitude to pursue the Hebrews over the sands than on the shore, but it certainly required more hardihood. But the unpursued departure which the good-will of Egypt refused, their common sense was not allowed to grant. Callousness was followed by infatuation, as even the pagans felt that whom God wills to ruin He first drives mad.
This explanation implies that to harden Pharaoh's heart was to inspire him, not with wickedness, but with nerve.
And as far as the original language helps us at all, it decidedly supports this view. Three different expressions have been unhappily rendered by the same English word, to harden; but they may be discriminated throughout the narrative in Exodus, by the margin of the Revised Version.
One word, which commonly appears without any marginal explanation, is the same which is employed elsewhere about "the cause which is too _hard_ for" minor judges (Deut. i. 17, cf. xv. 18, etc.). Now, this word is found (vii. 13) in the second threat that "I will harden Pharaoh's heart," and in the account which was to be given to posterity of how "Pharaoh hardened himself to let us go" (xiii. 15). And it is said likewise of Sihon, king of Heshbon, that he "would not let us pass by him, for the Lord thy God hardened his spirit and made his heart strong" (Deut. ii. 30). But since it does not occur anywhere in all the narrative of what God actually did with Pharaoh, it is only just to interpret this phrase in the prediction by what we read elsewhere of the manner of its fulfilment.