He increaseth the nations - Mr. Good translates, He letteth the nations grow licentious. Pride, fullness of bread, with extensive trade and commerce, produce luxury; and this is ever accompanied with profligacy of manners. When, then, the cup of this iniquity is full, God destroys the nation, by bringing or permitting to come against it a nation less pampered, more necessitous, and inured to toil.
He enlargeth the nations - Often permits a nation to acquire an accession of territory, and afterwards shuts them up within their ancient boundaries, and often contracts even those. All these things seem to occur as natural events, and the consequences of state intrigues, and such like causes; but when Divine inspiration comes to pronounce upon them, they are shown to be the consequence of God's acting in his judgment and mercy; for it is by him that kings reign; it is he who putteth down one and raiseth up another.
He increaseth the nations, and destroyeth them - He has entire control over them. The sources of prosperity are in his hand, and at his pleasure he can visit them with famine, pestilence, or war, and diminish their numbers and arrest their prosperity. Dr. Good renders this very improperly, “He letteth the nations grow licentious;” but the word שׂגא śâgâ' never has this sense. It means, to make great; to multiply; to increase.
And straiteneth them again - Margin, “leadeth in.” So the word נחה nâchâh means. The idea is, that he increases a nation so that it spreads abroad beyond its usual limits, and then at his pleasure leads them back again, or confines them within the limits from where they had emigrated.