If you read about a tree, and there is a description, you have to grow that tree in your mind. So that's an active way of looking at media, whereas a movie or a TV will be passive, because they are showing you the tree. In the same way, when somebody sings a song for you, those words get so much in the foreground, that even if you take a minor key of music and then put like happy lyrics to it and people think it's a happy song. So, in a song, you are told what to feel, whereas, in an instrumental music, you get as much out of it as you are willing to put into it.