The second word is explained in the margin as meaning _to make strong_. Already God had employed it when He said "I will _make strong_ his heart" (iv. 21), and this is the term used of the first fulfilment of the menace, after the sixth plague (ix. 12). God is not said to interfere again after the seventh, which had few special terrors for Pharaoh himself; but from henceforth the expression "to make _strong_" alternates with the phrase "to make _heavy_." "Go in unto Pharaoh, for I have made heavy his heart and the heart of his servants, that I might show these My signs in the midst of them" (x. 1).
It may be safely assumed that these two expressions cover between them all that is asserted of the judicial action of God in preventing a recoil of Pharaoh from his calamities. Now, the strengthening of a heart, however punitive and disastrous when a man's will is evil (just as the strengthening of his arm is disastrous then), has in itself no immorality inherent. It is a thing as often good as bad,--as when Israel and Joshua are exhorted to "Be _strong_ and of a good courage" (Deut. xxxi. 6, 7, 23), and when the angel laid his hand upon Daniel and said, "Be strong, yea, be strong" (Dan. x. 19). In these passages the phrase is identical with that which describes the process by which Pharaoh was prevented from cowering under the tremendous blows he had provoked.
The other expression is to make heavy or dull. Thus "the eyes of Israel were _heavy_ with age" (Gen. xlviii. 10), and as we speak of a _weight_ of honour, equally with the heaviness of a dull man, so we are twice commanded, "Make heavy (honour) thy father and thy mother"; and the Lord declares, "I will make Myself heavy (get Me honour) upon Pharaoh" (Deut. v. 16, Exod. xx. 12, xiv. 4, 17, 18). In these latter references it will be observed that the making "strong" the heart of Pharaoh, and the making "Myself heavy" are so connected as almost to show a design of indicating how far is either expression from conveying the notion of immorality, infused into a human heart by God. For one of the two phrases which have been thus interpreted is still applied to Pharaoh; but the other (and the more sinister, as we should think, when thus applied) is appropriated by God to Himself: He makes Himself heavy.
It is also a curious and significant coincidence that the same word was used of the burdens that were made _heavy_ when first they claimed their freedom, which is now used of the treatment of the heart of their oppressor (v. 9).
It appears, then, that the Lord is never said to debauch Pharaoh's heart, but only to strengthen it against prudence and to make it dull; that the words used do not express the infusion of evil passion, but the animation of a resolute courage, and the overclouding of a natural discernment; and, above all, that every one of the three words, to make hard, to make strong, and to make heavy, is employed to express Pharaoh's own treatment of himself, before it is applied to any work of God, as actually taking place already.
Nevertheless, there is a solemn warning for all time, in the assertion that what he at first chose, the vengeance of God afterward chose for him. For indeed the same process, working more slowly but on identical lines, is constantly seen in the hardening effect of vicious habit. The gambler did not mean to stake all his fortune upon one chance, when first he timidly laid down a paltry stake; nor has he changed his mind since then as to the imprudence of such a hazard. The drunkard, the murderer himself, is a man who at first did evil as far as he dared, and afterwards dared to do evil which he would once have shuddered at.