Compare Exodus 19:4. The "so," which the King James Version supplies in the next verse, should he inserted before "spreadeth," and omitted from Deuteronomy 32:12. The sense is, "so He spread out His wings, took them up," etc.

As an eagle stirreth up her nest - Flutters over her brood to excite them to fly; or, as some think, disturbs her nest to oblige the young ones to leave it; so God by his plagues in Egypt obliged the Israelites, otherwise very reluctant, to leave a place which he appeared by his judgments to have devoted to destruction.
Fluttereth over her young - ירחף yeracheph, broodeth over them, communicating to them a portion of her own vital warmth: so did God, by the influences of his Spirit, enlighten, encourage, and strengthen their minds. It is the same word which is used in Genesis 1:2.
Spreadeth abroad her wings, etc. - In order, not only to teach them how to fly, but to bear them when weary. For to this fact there seems an allusion, it having been generally believed that the eagle, through extraordinary affection for her young, takes them upon her back when they are weary of flying, so that the archers cannot injure them but by piercing the body of the mother. The same figure is used Exodus 19:4 (note); in the note. The נשר nesher, which we translate eagle, is supposed by Mr. Bruce to mean the rachama, a bird remarkable for its affection to its young, which it is known actually to bear on its back when they are weary.

As an eagle stirreth up her nest, (f) fluttereth over her young, spreadeth abroad her wings, taketh them, beareth them on her wings:
(f) To teach them to fly.

As an eagle stirreth up her nest,.... Her young ones in it, to get them out of it: Jarchi says the eagle is merciful to its young, and does not go into its nest suddenly, but first makes a noise, and disturbs them with her wings, striking them against a tree or its branches, that so they being awakened may be fitter to receive her: with respect to literal Israel, Egypt was their nest, where they were who were then in their infant state, lay like young birds in a nest; and though it was a filthy one and where they were confined, yet they seemed sometimes as if they did not care to come out of it; until the Lord made use of means to get them out, by the ministry of Moses and Aaron, by suffering their taskmasters to make their bondage heavier, and by judgments inflicted on the Egyptians, which made them urgent upon them to depart: with respect to spiritual Israel, their nest is a state of unregeneracy, in which they are at ease, and do not care to be awakened and stirred out of it; but the Lord, in love to them, awakens them, stirs them up, and gets them out, by sending his ministers to arouse them, by letting in the law into their consciences, which works a sense of wrath, by convincing them by his Spirit of their sin and danger, opening their eyes to see their wretched and miserable estate and condition, and by exerting his almighty power, plucking them as brands out of the burning:
fluttereth over her young; by that means to get them out of the nest, and teach them to fly, as well as to preserve them from the attempts of any to take them away; for though some writers represent the eagle as hardhearted to its young, casting them out of the nest, when they are taken care of by the offifrage; yet this is to be understood of it when tired with nursing, and when its young are capable of taking care of themselves; or of some sort of eagles; for Aelianus (r) testifies, that of all animals the eagle is most affectionate to its young, and most studiously careful of them; when it sees anyone coming to them, it will not suffer them to go away unpunished, but will beat them with its wings and tear them with its nails: Jarchi thinks this phrase is expressive of the manner of its incubation on its young; it does not, he says, lie heavy upon them, but lifts up herself, and touches them as if she did not touch them; but it rather signifies the motion she makes with her wings to get her young, when fledged, out of the nest, and to teach them to make use of their wings, as she does; and we are told that young eagles, when their wings are weak, will fly about their dams and learn of them to fly (s); and hence it is that young eagles while they are eating flutter their wings, that motion being so natural to them, and seeing their dams do so likewise (t): this passage seems to contradict a notion that has obtained with some, that an eagle only breeds one at a time; the philosopher says (u), the eagle lays three eggs and casts out two of them; according to the verse of Musaeus, it lays three, casts out two, and brings up one; and so, he says, it commonly is the case: but sometimes three young ones are seen together; and the black eagles are more kind to their young, and careful in the nourishment of them; and the same says Pliny (w); yea we are told, that sometimes seven are seen in a nest (x):
spreadeth abroad her wings taketh them, beareth them on her wings; that is, spreads forth her wings when she flutters over her young to instruct them; or she does this in order to take up her young and carry them on them: it is said that eagles fly round their nest, and vary the flights for the instruction of their young; and afterwards taking them on their backs, they soar with them aloft, in order to try their strength, shaking them off into the air: and if they perceive them too weak to sustain themselves, they with surprising dexterity fly under them again, and receive them on their wings to prevent their fall (y); See Gill on Exodus 19:4; thus the Lord, comparable to this creature for his affection to the people of Israel, his care of them, and his strength to bear and carry them, did bear them as on eagles' wings, and carried and saved them all the days of old; even Christ, the Angel of Jehovah's presence, the rock of salvation they rejected, see Exodus 19:4; and all this in a spiritual and evangelic sense may be expressive of the gracious dealings of God with his spiritual Israel; teaching and enabling them to mount up with wings as eagles, to soar aloft in the exercise of faith, hope, and love, entering thereby within the vail into the holiest of all, and living in the constant and comfortable expectation of heaven and happiness; and of the Lord's taking his people up from the low estate in which they are, and raising them up to near communion with himself, bearing them on his heart, in his hands, and on his arm, supporting them under all their afflictions, and carrying them, through all their troubles and difficulties, safe to eternal glory and happiness.
(r) Hist. Animal. l. 2. c. 40. (s) Suidas, vol. 1. p. 89. (t) Bochart. Hierozoic. par. 2. l. 2. c. 3. col. 178. (u) Aristot. Hist. Animal. l. 6. c. 6. (w) Nat Hist. l. 10. c. 3. (x) Vid. Bochart ut supra. (t)) (y) See Harris's Voyages, vol. 1. B. 1. c. 2. sect. 14. p. 486.

As an eagle . . . fluttereth over her young--This beautiful and expressive metaphor is founded on the extraordinary care and attachment which the female eagle cherishes for her young. When her newly fledged progeny are sufficiently advanced to soar in their native element, she, in their first attempts at flying, supports them on the tip of her wing, encouraging, directing, and aiding their feeble efforts to longer and sublimer flights. So did God take the most tender and powerful care of His chosen people; He carried them out of Egypt and led them through all the horrors of the wilderness to the promised inheritance.

"As an eagle, which stirreth up its nest and soars over its young, He spread out His wings, took him up, carried him upon His wings." Under the figure of an eagle, which teaches its young to fly, and in doing so protects them from injury with watchful affection, Moses describes the care with which the Lord came to the relief of His people in their helplessness, and assisted them to develop their strength. This figure no doubt refers more especially to the protection and assistance of God experienced by Israel in its journey through the Arabian desert; but it must not be restricted to this. It embraces both the deliverance of Israel out of Egypt by the outstretched arm of the Lord, as we may see from a comparison with Exodus 19:4, where the Lord is said to have brought His people out of Egypt upon eagles' wings, and also the introduction into Canaan, when the Lord drove the Canaanites out from before them and destroyed them. This verse contains an independent thought; the first half is the protasis, the second the apodosis. The nominative to "spreadeth abroad" is Jehovah; and the suffixes in יקּחהוּ and ישּׂאהוּ ("taketh" and "beareth") refer to Israel or Jacob (Deuteronomy 32:9), like the suffixes in Deuteronomy 32:10. As כּ cannot open a sentence like כּאשׁר, we must supply the relative אשׁר after נשׁר. קנּו העיר, to waken up, rouse up its nest, i.e., to encourage the young ones to fly. It is rendered correctly by the Vulgate, provocans ad volandum pullos suos; and freely by Luther, "bringeth out its young." "Soareth over its young:" namely, in order that, when they were attempting to fly, if any were in danger of falling through exhaustion, it might take them at once upon its powerful wings, and preserve them from harm. Examples of this, according to the popular belief, are given by Bochart (Hieroz. ii. p. 762). רחף, from רחף to be loose or slack (Jeremiah 23:9): in the Piel it is applied to a bird in the sense of loosening its wings, as distinguished from binding its wings to its body; hence (1) to sit upon eggs with loosened wings, and (2) to fly with loosened wings. Here it is used in the latter sense, because the young are referred to. The point of comparison between the conduct of God towards Jacob and the acts of an eagle towards its young, is the loving care with which He trained Israel to independence. The carrying of Israel upon the eagle's wings of divine love and omnipotence was manifested in the most glorious way in the guidance of it by the pillar of cloud and fire, though it was not so exclusively in this visible vehicle of the gracious presence of God as that the comparison can be restricted to this phenomenon alone. Luther's interpretation is more correct than this - "Moses points out in these words, how He fostered them in the desert, bore with their manners, tried them and blessed them that they might learn to fly, i.e., to trust in Him," - except that the explanation of the expression "to fly" is narrowed too much.

Her nest - Her young ones in the nest; which she by her cry and motion provoketh to fly. Her wings - As preparing herself to fly. On her wings - Or, as on her wings, that is, gently, and tenderly and safely too, as if she carried them not in her claws for fear of hurting them, but upon her wings. Some say, the eagle doth usually carry her young ones upon her wings.