With a butterfly effect/Groundhog Day premise, I expected the story to have a clear goal for what needed to be "fixed". I kind of like that it didn't, but it did make me go down the "what's the point of life" rabbit hole more than once. 
 There was a clearly defined theme, most notably stated as "Izzy is still Izzy", that ran throughout the course of the story. Is it true that no matter what choices we make in life, we will still be ourselves when all is said and done, and that there is no other way to be? Hmmmm. 
 P.S. Kudos for use of the word palimpsest, def: a manuscript or piece of writing material on which the original writing has been effaced to make room for later writing but of which traces remain; OR something reused or altered but still bearing visible traces of its earlier form. 
 P.S.S. I didn't know there was a voluntary night watch to protect St. Paul's Cathedral from ruin. Cool. 
 Favorite Quotes 
 "I don't think any of them are themselves anymore," Sylvie said. Ursula tried to imagine not being Ursula but was defeated by the impossibility of the task. 
 Her memories seemed like a cascade of echoes. 
 It was a lovely late-September afternoon, crisp as an apple. 
 Amor fati...A simple acceptance of what comes to us, regarding it as neither bad nor good. 
 [S]he skipped along the path, singing tra-la-la. Nancy was a girl who really did sing tra-la-la. Ursula wished she was that kind of girl. 
 A buttery, unseasonal sun was trying hard to nudge its way through the thick velvet curtains.