How does the writer convey the power of nature in Edwin Morgan's "Slate"?

Morgan convey's the power of nature in "Slate" through the use of various sound techniques including sibilance. " must streak, surely strike,seldom stroke,"The repeated "S" sound here is indicative of a moving force, making the landscape Morgan is describing seem lively as opposed to a flat entity. Through this he is able to invoke a sense of power through the activity of Scotland, especially in contrast to the "empty hunger" of men, a contrast which again proves just how alive the island is.Morgan also uses sound techniques to describe the hills of Scotland."Drumlins blue asbruises"The plosive sound in the alliteration of "blue as bruises" creates a dull, thudding sound, showing a more violent side to the liveliness of Scotland. Again, this shows power, this time through the medium of strength, which is echoed in the bruising image, proving Scotland to be a strong and therefore powerful force.