Wow, wildcat, you pose many great questions. I have noticed that there are many kinds of pain. I too wonder why if life is so good, why I am still depressed and sometimes manage to get through the day feeling okay and others are horrid. I feel depressed all the time, so I don't have the mood swings you refer to, but I have my bad depressed days and my "good" depressed days and none of those are too good. I am grateful for those though. I also know I have many tools as resources and can make my day worse with those negative thoughts or make it better. Sometimes I just don't have the strength to fight those negative thoughts or work to make it better, not cry, not sleep all day, etc. and that makes me angry but only at me. I try to find things to be grateful for (and there are many in my life) still I seem to focus on the negative - even with a daily list- what's up with that.
I don't think there is an explanation or a justification - meaning I don't think you fit the situation to the mood. And sometimes the mood doesn't fit the situation! It seems so complicated, yet it is so simple - a way to get better at my finger tips (literally) as well as with the meds, therapy and work (another form of therapy for me).
I am glad that you are enjoying the day, relaxing, taking it easy and not consumed by the other things in life and btw when you remember why the red leaves fall first - I'd be curious to know the answer! Our leaves are just now turning and haven't started to fall. I will watch them - the simple pleasures in life! Did you, as a child, bunch up the leaves and /or rake them up and then run and jump and cover yourself in them. It was such fun for me!
Thanks for stimulating my mind with such interesting questions and thoughts!