Is it possible to make yourself melancholy by listening to/singing/humming the same tune over and over? Because I may have accomplished that this afternoon => this evening. I have been feeling a bit down ever since earlier today, when I realized a Bach cantata that I 'd always associated with a feeling of positive religious affirmation* is in fact about being so sick and tired of life you're basically pleading with God to take you away from it all. But the melodies are still so beautiful I've been hearing them in the back of my head all day.
* On the part of the "narrative voice" of the cantata, not me personally.