text: While a piece of Western music generally has a home key , a passage within it may modulate to another key , which is usually closely related to the home key , that is , close to the original around the circle of fifths .
simplified: A piece of Western music usually has a home key , and a passage within it may modulate to another key , which is usually closely related to the home key . ( Usually , close to the original around the circle of fifths . )