When materials are mechanically lifted, they have the potential to swing and strike workers. As the load is lifted, the materialsmay swing, twist, or turn. When an object is rolling, moving, or sliding on the same level at which the worker is located.
These lines are taken from "The Lake Isle of Innisfree" by William Butler Yeats. The theme of these lines is related to the peace. The speaker might be feeling trapped, bussy, sad and that is the reason why his motivation in life is to achieve some peacefulness. So we can say that the main theme is: Peace.
