Re-reading the Lord of the Rings, Chapter 48

The last chapter dwelt on Denethor's tragedy and that tragedy was one of a world of planning, in which there is no room for emotions and in particular not for mercy.

In this chapter now the Rohirrim find mercy, the mercy of a world unexplored, but friendly to them, and are asked for mercy in return, namely to let that world and its inhabitants be in times to come.

Is it so wrong for man to assume that when he finds the world ready for his needs, that he's been shown mercy?

People have lived on this earth for a long time, and every act of making the world more inhabitable is an act of mercy, for slowly these acts change the face of the earth, owing to the time that trees need to grow. And what is that lets one consider the future and the lucky ones that will roam its widths? Is it not that one considers one's place and responsibility, the share of life that has taken on one's shape and strives to stay true to life itself, from whence it came and whither it will go?

And all this is done blindly, unknowingly, by cowing in a way, in instinctive accordance with the flow of all things. This is the matter that Gandalf strives to shape, but not replace.