He hath done might This means, "he hath wrought powerfully." The arm of God is contrasted with every other aid: as in Isaiah, "I looked, and there was none to help," (Isaiah 63:5;) "therefore," says he elsewhere, "his arm brought salvation unto him; and his righteousness, it sustained him," (Isaiah 59:16.) Mary therefore means: God rested satisfied with his own power, employed no companions in the work, called none to afford him aid. What immediately follows about the proud may be supposed to be added for one of two reasons: either because the proud gain nothing by endeavoring, like the giants of old, to oppose God; or, because God does not display the power of his arm for salvation, except in the case of the humble, while the proud, who arrogate much to themselves, are thrown down To this relates the exhortation of Peter, "Humble yourselves under the mighty hand of God," (1-Peter 5:6.) He hath scattered [1] the proud in the thought of their heart [2] This expression is worthy of notice: for as their pride and ambition are outrageous, as their covetousness is insatiable, they pile up their deliberations to form an immense heap, and, to say all in a single word, they build the tower of Babel, (Genesis 11:9.) Not satisfied with having made one or another foolish attempt beyond their strength, or with their former schemes of mad presumption, they still add to their amount. When God has for a time looked down from heaven, in silent mockery, on their splendid preparations, he unexpectedly scatters the whole mass: just as when a building is overturned, and its parts, which had formerly been bound together by a strong and firm union, are widely scattered in every direction.

Footnotes

1 - dieschorpisen,, he utterly discomfits, a metaphor derived from putting to flight a defeated enemy. The word not unfrequently occurs in the Septuagint, but very rarely in the classical writers; though one example is adduced by Kuinoel from Aelian, Var. Hist. 13:46: tous men dieschozpisen, ohus, (read tous) de apechteiene." -- Bloomfield's Greek Testament.

2 - "La ou nous avons rendu, Il a dissipe, le mot Grec signifie proprement, Il a escarte ou espars."

Hath showed strength with his arm - The "arm" is the symbol of strength. The expression in this and the subsequent verses has no particular reference to his mercy to Mary. From a contemplation of His goodness to her, she enlarges her views to a contemplation of His goodness and power in general, and to a celebration of the praises of God for all that he has done to all people. This is the nature of true piety. It does not terminate in thinking of God's mercy toward ourselves. It thinks of others, and praises God that others also are made partakers of His mercy, and that His goodness is manifested to all His works.
He scattereth the proud - He hath often done it in time of battle and war. When the proud Assyrian, Egyptian, or Babylonian had come against the people of God, He had often scattered them and driven away their armies.
In the imagination of their hearts - Those who were lifted up or exalted in their own view. Those who "thought themselves" to be superior to other men.

He hath showed strength - Or, He hath gained the victory, εποιησε κρατος. The word κρατος is used for victory, by Homer, Hesiod, Sophocles, Euripides, and others.
With his arm - Grotius has well observed, that God's efficacy is represented by his finger, his great power by his hand, and his omnipotence by his arm. The plague of lice was the finger of God, Exodus 7:18. The plagues in general were wrought by his hand, Exodus 3:20, And the destruction of Pharaoh's host in the Red Sea, which was effected by the omnipotence of God, is called the act of his arm, Exodus 15:16.
He hath scattered - Διεσκορπισεν, hath scattered abroad; as a whirlwind scatters dust and chaff.
The proud - Or haughty, ὑπερηφανους; from ὑπερ above, and φαινω I show - the haughty men, who wish to be noticed in preference to all others, and feel sovereign contempt for all but themselves. These God scatters abroad - instead of being in his sight, as in their own, the most excellent of the earth, he treats them as straw, stubble, chaff, and dust.
In the imagination of their hearts - While they are forming their insolent, proud, and oppressive projects - laying their plans, and imagining that accomplishment and success are waiting at their right hand, the whirlwind of God's displeasure blows, and they and their machinations are dissipated together.

He hath shewed strength with his (t) arm; he hath (u) scattered the proud in the (x) imagination of their hearts.
(t) Here many more words than necessary are used, which the Hebrews use very much: and "arm" here is taken for strength.
(u) Even as the wind does to the chaff.
(x) He has scattered them, and the imagination of their hearts; or, by and through the imagination of their own hearts; so that their wicked counsel turned to their own destruction.

He hath showed strength with his arm,.... Of almighty power, in the business of the incarnation, and in working out salvation for his people; which is done by his own arm, he being mighty to save, and travelling in the greatness of his strength; see Isaiah 63:1.
He hath scattered the proud in the imagination of their hearts; whom he always resists, and both in providence and grace, takes such methods, as tend to humble and confound them: here particularly, it may regard the proud and haughty Jews; who imagined nothing less, than that the Messiah would be born of one of the rich and noble families in Judea; that he would appear as a temporal prince, and set up a temporal kingdom in great state and splendour, and make them a free and flourishing people: when instead of this, he was to be born of a poor virgin, of whom they disdainfully say, is not his mother called Mary? who was of Nazareth in Galilee, of which it is said, shall Christ come out of Galilee? or any good thing out of Nazareth? A virgin betrothed to a carpenter, and her son of that business also, with which both were flouted; and because of this meanness, the Messiah was rejected by them; and thus were they scattered and confounded in their imaginations.

He hath wrought strength with his arm - That is, he hath shown the exceeding greatness of his power. She speaks prophetically of those things as already done, which God was about to do by the Messiah. He hath scattered the proud - Visible and invisible.