A theory I have is that all music can be categorized roughly into six categories based on the underlying feelings and emotions that are being expressed in that music.
1. Positively Self-Other related: I'm proud of myself, happy with myself, and happy with the people (or one specific person) around me. Can also mean happy with life itself, nature, God, whatever. Example: It's a wonderful world.
2. Positively Self related: Just proud of myself, I'm the hero, I'm happy with myself, no matter what others may think of that. Example: Tiger Man
3. Positively Other related: Connected with life, nature or in love with someone I feel connected to and she/he feels connected to me. I give love and get love in return. Example: I Love You, Because
4. Negatively Self related: I don't count, people don't see me, I'm not proud of myself, I have a low self esteem. Example: Feel So Bad
5. Negatively Other related: I can't connect with somebody else, or with nature, God, life itself. I feel rejected, my love isn't returned. I long for something, but can't reach what I long for. Example: well, see your list here. Not just depression, but a longing for something unreachable.A longing for connectedness. (Nash would call it a life time longing for the connectedness with his twin brother I guess. Or with his mother, for that matter).
6. Negatively Self-Other related: don't feel good about myself, I don't count, people don't see me, I'm nothing and I am not connected to anything or anyone else. Life sucks. I don't like life anymore: and this is where real depression comes in. Example: I'm so lonesome, I could cry.
This theory is based on the work of Dutch professor Hubert Hermans. His theory in Dutch: http://nl.wikipedia.org/wiki/Zelfkonfrontatiemethode
Would be interesting to categorize Elvis' self chosen music through the years...