Response to tone is the subject matter. To paraphrase Emily Dickinson, the song is not in the robin it is in us.
Because a child responds to tone I listen. Out of that response grows curiosity about how others respond to tone. Out of that comes the ability to listen empathetically, and the desire to learn how the people we call composers have dealt with tone.
Learning to read that caring quality is not easy. But it can be done if the first step is recognition that the individual's response to tone is the necessary element.