For Israel has forgotten his Maker and built palaces; And Judah has multiplied fortified cities; But I will send a fire on his cities, And it will devour its fortresses."
A life lived after the flesh will bring a person to emptiness. Pursuing your own fleshly ambitions will not bring you satisfaction but only a deeper hunger that cannot be fulfilled. It'll yield no meal; it's all chaff. You go to eat it and there's no nourishment, there's nothing there. Life becomes empty like chaff.