Recent amazing post-canon fic "The Summing Up" by @melorasalive brought to my attention that Garak's final line in DS9 was most likely a reference to this quote:
"I could part without a pang with every possession I have. We live in uncertain times and our all may yet be taken from us."
...from a book called "The Summing Up" by W. Somerset Maughn, which seems to be a very Garak-esque autobiography...
And since I had just read The Calling (short follow-up to ASIT) before reading the fic, the title jumped out at me, because in that story Garak refers to a particular phenomenon as the "summing up."
So I'm thinking maybe Andy was purposefully channeling/drawing upon this guy's work, either because he knew or became aware of the reference, or maybe, since he did write the journal entries during the show, he imparted knowledge of this work to whoever wrote the line in the show and it ended up in there. If not, this is a lot of coincidence, and you know what Garak says about coincidences...