The Lord shall smite thee with madness and blindness. This punishment is very often referred to by the Prophets, when God is said to smite the wicked with a spirit [1] of giddiness and madness, to make them drunk with astonishment. Now, whatever God declares respecting this blindness or fury of mind, has a wide application; for hence it arises that the wicked rush willfully into vile lusts, shudder at no crime, are hurried headlong to destruction, are utterly deprived of discretion, throw away the remedies which are in their hands; and although the carnal sense is not greatly disturbed by this form of vengeance, still it is much more severe and awful than any bodily disease. The Poets imagined that wicked men were agitated and terrified by the furies, because experience taught them that it was not without a secret impulse from God that they became so senseless, when, their minds being affected, they were like beasts in the shape of men. Even heathens, then, perceived that when the wicked are given over to a reprobate mind, God thus manifests Himself as the just Avenger of their crimes. And so it is in all cases of "astonishment;" for it is plain that those who are thus stupified by their miseries, are prostrated by the hand of God.

Footnotes

1 - C gives no references here. It is probable that the passage, which he most had in his mind, was Isaiah 19:14, "The Lord hath mingled a perverse spirit;" in V., "Dominus miscuit in medio ejus spiritrum vertiginis, etc." His own Commentary on these words is, "The expression is metaphorical, as if one were to mix wine in a cup, that the Lord thus intoxicates the wise men of this world so that they are stunned and amazed, and can neither think nor act aright." Calvin Soc. edit., [27]vol. 2, p. 64. He also might refer to Isaiah 51:17; Jeremiah 25:15; Psalm 60:3, etc.

Mental maladies shah be added to those sore bodily plagues, and should Deuteronomy 28:29-34 reduce the sufferers to powerlessness before their enemies and oppressors.
Blindness - Most probably mental blindness; compare Lamentations 4:14; Zephaniah 1:17; 2-Corinthians 3:14 ff.

The Lord shall smite thee with madness - שגעון shiggaon, distraction, so that thou shalt not know what to do.
And blindness - עורון ivvaron, blindness, both physical and mental; the גרב garab, (Deuteronomy 28:27), destroying their eyes, and the judgments of God confounding their understandings.
Astonishment - תמהון timmahon, stupidity and amazement. By the just judgments of God they were so completely confounded, as not to discern the means by which they might prevent or remove their calamities, and to adopt those which led directly to their ruin. How true is the ancient saying, Quos Deus vult perdere, prius dementat! "Those whom God is determined to destroy, he first infatuates." But this applies not exclusively to the poor Jews: how miserably infatuated have the powers of the continent of Europe been, in all their councils and measures, for several years past! And what is the result? They have fallen - most deplorably fallen!

The Lord shall smite thee with madness,.... At the calamities befallen them, and through the force of diseases on them:
and blindness; not of body, but of mind; with judicial blindness and hardness of heart:
and astonishment of heart; at the miserable condition they and their families should be in.

madness, and blindness, and astonishment of heart--They would be bewildered and paralyzed with terror at the extent of their calamities.

Blindness - Of mind, so that they shall not know what to do: Astonishment - They shall be filled with wonder and horror because of the strangeness and soreness of their calamities.