The Dictionary of Obscure Sorrows
n. the insomnia-borne jolt of awareness that you will die, that these passing years aren’t just scenes from a dress rehearsal, rounds of an ongoing game or chapters in a story you’ll be telling later, but are footprints being lapped by the steadily gathering tide of an unfathomable abyss" . . .
Thank you Grant for pointing me to The Dictionary of Obscure Sorrows, my new favorite thing on the internet. Also one of my least favorite, insofar as it's one of those things I absolutely wish I had written myself.