In Amos 4:2 God swore by His holiness, all of His moral integrity, His very nature. He also swore by Himself (Amos 6:8), indicating everything that He is and His sovereignty over all creation. Israel was not impressed. So God says, "Look, I have sworn by My holiness and by Myself, and that didn't carry any weight with you. So now I will swear by something so great—your own pride—that you can't refuse!" What irony! God says if He swears by something of theirs, it may mean more to them than if He swears by something of His!
This passage also shows that when man gets out of step with God, then nature too begins to suffer. Beauty begins to be replaced by ugliness. We begin to see huge piles of slag, polluted rivers, foul-smelling garbage dumps, expanding deserts, and denuded forests. Finally, when the land begins to vomit the people out (Leviticus 18:24-28), they may show a belated interest in God and His truth, but it will be too late to stop the destruction. The time is right—the fruit is ripe, so God will punish them.
Consider what is currently happening in our Western nations of Israel. God shows a connection between nature and human morality; "natural" disasters are acts of God in response to the moral condition of the people. If men will treat other men, created in the image of God, in an immoral way, how will they treat the land, forests, rivers, lakes, and oceans? Because these things seemingly cannot fight back, man will abuse them with no fear of reprisal. But God says that the environment will fight back and vomit them out!
Instead of rain falling in a gentle mist, it will roar like an avalanche until the inhabitants cannot cope with it. The rivers will swell and flood the land in anger, washing the topsoil into the sea. In other areas, fire will sweep over forests and farmlands, destroying everything in its path. Windstorms like hurricanes and tornadoes will devastate the cities and countryside, endangering the lives and livelihoods of the people. Earthquakes will increase in both frequency and power, costing thousands of lives and billions of dollars of damage. These disasters will mount to such an intensity that the people of modern Israel may seek repentance, but it will be too late. God will not pass by anymore.