I saw The Brothers Grimm on Sunday, and was pretty happy with it. It was, as I suspected, the "mainstream Hollywood action film" version of The Adventures of Baron Munchhausen. Although the script wasn't Terry Gilliam's, their did seem to be a lot of coincidence with Munchhausen.
Neal Stephenson has made a huge impact (in sheer weightage) on book shelves with his overly baroque, overly wordy treatise on The Age of Enlightenment. I've read two parts of it now, The Diamond Age ("The End of The Age of Enlightenment" in my eyes, as it chronicles a lot of the "return of Magic and Fairy Tales" as well as sets the precedence for the style of writing to come in the later parts) and Cryptonomicom (honestly, I have no idea what the themes there represented). Quicksilver sits on my shelf in hard cover just in case I ever feel like actually reading it. Maybe the day Stephenson writes a short 100-page "key" to decipher his treatise with I might make the effort to read all of it. The important thing to note is that obviously it is a major theme that offers a lot of infatuation for the author, as it has spawned thousands of pages and millions of words of writing. Baroque music (and culture) is said to have swept in the Age of Enlightenment, and Stephenson has remarked that the irony of his series being long and baroque was intentional.
On the other hand, David Brin has left his fiction writing mostly free of it, but he's spent many interesting website rants and blogsite posts on the subject. Some of which is fascinating reading and all of it is clear text that can be easily followed.
Somewhere along the line I think Terry Gilliam (subconsciously or not) decided to create his own doctoral dissertation on the birth and life of the Age of Enlightenment. I don't think that, like Stephenson, Gilliam has any sort of "grand plan" for a major cycle, but with his love of certain themes I do think that there is a raw sort of continuity between his works. Munchhausen and Brothers Grimm are both epics about "the last Magic", but where they differ is quite interesting. Munchhausen is a romantic fairy tale (in the modern Disney sense) in which a good story and a bit of Magic can conquer and invading army. Whereas The Brothers Grimm is a dark, twisted fairy tale (in the old Germanic spook stories that are passed down primarily by genetics, or so it would seem) in which we are reminded that we've gained so much more "security" in the passing of those old dreams. There's good irony in that the romantic Disney-esque one was dark and budget crunched where the dark, twisted one was "sold out" and done at a Disney budget, with Disney actors and Disney effects. As an evil, twisted movie about the horrors of fairy tales done in the style of the Pirates of the Caribean films The Brothers Grimm amused the hell out of me. I wonder how many other people can appreciate that depth of irony... that in reminding us of what Disney has asked us to forget as it Disney-ified our fairy tales, Gilliam was simultaneously Disney-ifying his own processes. I can't assume to believe that Gilliam did it on purpouse and created such brilliant irony on purpouse, but I admire it all the same.
So, back to the original point... in one you have "the beauty of Magic" and in the other you have "the ugliness of Magic". In both you see some of the weakness of the Age of Reason (which helped "give birth" to the Age of Enlightenment). It's interesting to note how Jonathan Price plays the themes of the worst of the Age of Reason in both films. In the characters of the Brothers Grimm themselves, however, you see the twinkling of the greatnesses of the Age of Enlightenment to follow. In a way, the Brother Grimm make a good Newton for Gilliam's work. In Stephenson's Baroque cycle, Newton features prominently (or so I've read second hand), as Stephenson thought that Newton was such an interesting pivot (he was steeped in old superstitions and ideas, but was also extremely instrumental at creating science as we know it today) I think that so too does the Brothers Grimm work in this capacity. The Brothers were brilliant cultural anthropologists (realizing that the folk lores around them really needed preserving in much of their ugly glory (speaking of which, The Aristocrats, cultural anthropology from Penn (of & Teller) is next on my movie TODO list)), and also did early work in linguistic, but their scientific and cultural works were steeped in the "magic" of the past.
If you add Brazil to the mix, you have a work detailing some of the failings of the Age of Enlightenment (I would say in this particular case it is the ghost of the transitionary Age of Reason haunting the Enlightenment... where science and technology subvert democracy and individualism through beauracracy). 12 Monkeys offers more legitimate criticism of the Age of Enlightenment as "a shrink for everyone" and attempting to scientifically control the human mind makes us all a little crazier.
The big thing missing from Gilliam's Age of Enlightenment cycle, and I would hope to see him produce such a thing, is a capstone film celebrating the Age of Enlightenment. Obviously this would take one heck of a script for him to pick it up, but the themes are there in his work, if somewhat buried: the power of the individual, the power of the human mind, the possibility for greatness inherent in humanity. I think The Fisher King does this somewhat (although I haven't seen the movie in years, so I don't recall it that well), but I guess I'm hoping for something cooler and more baroque, I guess.