This proof of progress in the book is confirmed by another feature. In the abstract given above it is easy to see that the judgments of the Lord upon Israel were of a twofold character. Some were physical--famine, drought, blight, locusts, earthquake; and some were political--battle, defeat, invasion, captivity. Now it is significant--and I do not think the point has been previously remarked--that not only are the physical represented as happening first, but that at one time the prophet seems to have understood that no others would be needed, that indeed God did not reveal to him the imminence of political disaster till He had exhausted the discipline of physical calamities. For this we have double evidence. In chapter iv. Amos reports that the Lord has sought to rouse Israel out of the moral lethargy into which their religious services have soothed them, by withholding bread and water; by blighting their orchards; by a pestilence, a thoroughly Egyptian one; and by an earthquake. But these having failed to produce repentance, God must visit the people once more: how, the prophet does not say, leaving the imminent terror unnamed, but we know that the Assyrian overthrow is meant. Now precisely parallel to this is the course of the Visions in chapter vii. The Lord caused Amos to see (whether in fancy or in fact we need not now stop to consider) the plague of locusts. It was so bad as to threaten Israel with destruction. But Amos interceded, and God answered, _It shall not be_. Similarly with a plague of drought. But then the Vision shifts from the realm of nature to that of politics. The Lord sets the plumbline to the fabric of Israel's life: this is found hopelessly bent and unstable. It must be pulled down, and the pulling down shall be political: the family of Jeroboam is to be slain, the people are to go into captivity. The next Vision, therefore, is of the End--the Final Judgment of war and defeat, which is followed only by Silence. Thus, by a double proof, we see not only that the Divine method in that age was to act first by physical chastisement, and only then by an inevitable, ultimate doom of war and captivity; but that the experience of Amos himself, his own intercourse with the Lord, passed through these two stages. The significance of this for the picture of the prophet's life we shall see in our next chapter. Here we are concerned to ask whether it gives us any clue as to the extant arrangement of his prophecies, or any justification for re-arranging them, as the prophecies of Isaiah have to be re-arranged, according to the various stages of historical development at which they were uttered.