Possibly my favorite piece of Chesterton's fiction...which is saying a lot.
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thoughts after my 4th read, fall 2021: not many to add, since I read it quickly (in roughly 24 hours), mostly to pull eugenics-related quotes from it for a paper I get to write this year. (eeh so excited!) Turnbull and MacIan are still the best. (and i never noticed that the first time the Girl sees MacIan, he's not only springing to her defense but springing to her defense WITH A MEDIEVAL SWORD IN HAND, and he's an excellent swordsman. so like...how is she not supposed to fall in love with him, exactly.)
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thoughts added after my 3rd read, spring 2021:
This book. Oh, me, this book. It makes me so happy. SO HAPPY. Evan MacIan, the brooding young Catholic Highlander, and his truculent opponent, the redheaded atheistic London Scotchman James Turnbull, have my heart in a way that no other Chesterton characters do--and yes, that includes even dear, dear Fr. Brown and darling, darling Flambeau. Fr. Brown and Flambeau are FANTASTIC. But Evan MacIan and James Turnbull give me palpitations.
Particular things that I appreciate very much:
-) Even though Evan MacIan is the hero, by no means is he perfect. Yes, he's on fire to convert the world; but he himself is in need of conversion. His character arc is one of the most interesting ones in the book. In other words, Chesterton isn't simplistic about this Catholic vs. atheist thing.
-) James Turnbull, the atheist, is such a good, sturdy, good-humored, honest fellow. I love him more every time I read the book.
-) "Sincerity" is one of the key values in the story. Both these guys are SO BEAUTIFULLY SINCERE.
-) That part where Turnbull is like "Ugh, nature-worshippers, can't stand 'em" and MacIan is like "Yeah me neither...but isn't that what you atheists are all about?" and Turnbull is like "You thought we WHAT? *splutters* This is a case for beer" and MacIan's like "But the duel--!" and Turnbull is like "BEER!" and so they go get a drink and it's the beginning of a buddyhood
-) The bromance.
-) And also the romance. (You can't ask for more than a book that has squeal-worthy bromance AND squeal-worthy romance.)
-) Professor Lucifer and his flying ship are THRILLING in the way that only the best (as in worst) villains and nightmares can be. Plus they have a little steampunk aesthetic going on? Anyway, the dreams of MacIan and Turnbull are two of the BEST chapters in the book. They make me so excited.
-) And also, THIS BOOK IS ONE LONG ANGRY BEAUTIFUL SONG AGAINST EUGENICS.
With the caveat that there is some extremely politically incorrect terminology (it's 1909, after all), I have....no issues with this book. The ending's a little wild, maybe even a tad esoteric, and I don't think I understand it very well yet; but it's BEAUTIFUL.
This book is just. Just beautiful. I love it to death.