They say you cannot compare apples with oranges. But, metaphors identify the similarities, instead of differences, between two unlike things. Beautiful isn't? Metaphors make complex concepts sound easier so that we can relate.
In music, metaphors help listeners identify with the lyricists' emotions. They help us imagine and visualize abstract concepts as a concrete image.
Here's a Kannada original song sung by Sunil Koshy of From Mug to Mike and I. The picture in this post is what came to my mind when I listened to the song below: