This is a phenomenal write-up on this subject. And your timing kind of creeps me out. In a good way. :)

Just yesterday I was reading about nostalgia, and I think about it often.

And then this morning I was inspired by a deep sadness while thinking about my childhood dog, who has been gone for 30 years.

Have you heard of "time slips"? When someone suddenly finds themselves in a different time? Of course, that's a more paranormal explanation, but interesting nonetheless.

Thank you for this thought-provoking piece. And also, happy to know another fan of the Dictionary of Obscure Sorrows!

CR