Mono no Aware.
Mono no aware (物の哀れ?), literally "the pathos of things", and also translated as "an empathy toward things", or "a sensitivity to ephemera", is a Japanese term used to describe the awareness of impermanence (無常 mujō ), or transience of things, and a gentle sadness (or wistfulness) at their passing.
Wikipedia has a whole entry on this stuff. I stumbled across it by accident trying to be a smart ass on Facebook about Japanese poetry forms (because I'm a haughty literate dipshit that knows there actually are multiple Japanese poetry forms.)
I think it's beautiful that this is an actual "thing", and that it happens enough that it has been given a title to describe the state. I am in this at least once a day, this small sadness for the passing of things.
In other news, I rescued a baby goldfinch from the sidewalk and took him to wildlife rehab. I got to watch him eat, and he sang to the lady who was feeding him like he sang to me. I'm so happy that he'll be okay.... I didn't mean to, but in my head I named him Oscar.
He's slightly non-photogenic in that picture, but he was so sweet and so tiny... I can't describe how small. He fell asleep in my hand and I could feel his little heart beat furiously and warmly.
And now he gets to be an adult goldfinch and the world is good for a little bit longer.