Definitions of “obsession” from various online dictionaries, both those I mentioned in the episode and some extras.
From Merriam Webster’s dictionary online https://www.merriam-webster.com/dictionary/obsession
From Dictionary.com: https://www.dictionary.com/browse/obsession
Collins Dictionary: https://www.collinsdictionary.com/dictionary/english/obsession
The Oxford Dictionary online: https://en.oxforddictionaries.com/definition/obsession
The Wikipedia page about obsession: https://en.m.wikipedia.org/wiki/Obsession
And the book on the history of obsession in Western thought and medicine that I referred to was:
Davis, Lennard J. (2008) Obsession: A History. University of Chicago Press.
The following article “You Know You’re Addicted to POTO When…” is based on a thread from the old and venerable, but sadly no longer online, PhantomoftheOpera.com message-board. LOL And I can tell you that there’s some truth in this list, as I’ve done quite a few of these and was like “good idea” at several others! (Note, you have to either answer or skip the blasted survey question to read the full article.)
“You Know You’re Addicted to POTO When” http://www.fanpop.com/clubs/the-phantom-of-the-opera/articles/11108/title/know-youre-addicted-poto-when
And here’s another, similar discussion thread. LOL And yes, some of these I’ve done, too!
“You Know You’re Obsessed With POTO When” http://www.fanpop.com/clubs/the-phantom-of-the-opera/forum/post/40908/title/know-youre-obsessed-with-poto-when
A similar listing, this time posted as a story on Fanfiction.net. LOL This time I haven’t done so many of these myself!
And there’s lots more such out there! Just Google “You know you’re obsessed with Phantom when”.
Here, meanwhile, are some typical discussions of obsession in the story of Phantom itself. I’ll be honest, though, I find them a bit shallow for the most part, mostly because they seem to lack an awareness of Disability/Mad history with which to contextualize their analysis. Not to mention, of course, the influence of the Gerik!
Hopkins, Vicki (2008). “Obsession”. Lessons From The Phantom of the Opera. http://thephantomslessons.blogspot.com/2008/03/obsession.html
Note. This latter piece by Vicki Hopkins has since been published as part of her book Lessons From the Phantom of the Opera, which is a collection of her essays from this blog. I have yet to read it, though, so I don’t know if the version of this article in the book is the same.