I can't give this any kind of reasonable structure. It's a ramble. I find if I try to compose this as an essay, I remain with a blank page. So here goes.
Before leaving the field, Whitehead literally assumes the mantle of O'Neill—an outward sign of inward transformation. After the ordeal of his degradation and derangement at the hands of O'Neill, and his mushroom trip, he becomes a master, even saying as much.
Though Whitehead breaks his oath (under coercion by O'Neill), his attainment transcends that of O'Neill because it still comes as the culmination of the Great Work. O'Neill forsook prayer and devotion, traditionally the inner work of alchemy, in reaction to a world turned upside down, and its pockets with it.
If I can map this onto Crowley's A∴A∴ structure, O'Neill achieved Adeptus Exemptus and turned away to become a Brother of the Left Hand Path. Whitehead's mushroom trip, the solve, reaches the coagula stage when the split-screen fuses back into one (with a sickening, very biological sound) and leaves him higher up the Tree of Life, having successfully crossed the Abyss. O'Neill, despite his seeming power, never managed to recombine the dissolved components of his inner matter as he eschewed the inner work. All that remains for him is death. He is toppled and effaced.
Upon his attainment, there's no sense that Whitehead is returning to his apprenticeship under his master—he's taking the manuscripts and mushrooms and striking out with his companions into the real world outside the hedge and mushroom circle, back into the battlefields of the English Civil War.
But what the hell does any of that have to do with the English Civil War?
I'm going to look at this from a Heideggerian angle while borrowing some terminology from Albert Borgmann as well. At this point, rather than spend time explicating those ideas, I'll direct the reader to this piece by Hubert Dreyfus and Charles Spinosa, which is a good introduction though not without its problems.
O'Neill rejects the focal practices that Whitehead still embraces, the prayer and devotion of inner alchemy, and rejects too the premodern master-apprentice model in favor of command-labor. I don't want to overreach and say O'Neill stands for capital as I'm not sure they've really reached that point (or that I can really produce a decent Marxian reading!) but it's clear that he sees those around him, and the world in general, in terms of resource (Bestand, or standing-reserve), which is an important part of modernity as Heidegger sees it. Incidentally, Heidegger's word for this quality of modernity, Gestell (usually translated enframing), even has a slight hauntological aspect—it's another word for skeleton, and hell, the only treasure they find in the pit is a skull.
The focal practices of traditional alchemy are forced to the margins by O'Neill—Whitehead's natural gift is stripped of its archaic religious trappings and literally harnessed to serve O'Neill in his acquisition of the treasure, a treasure that presumably (I believe there are some lines in the film about what he wants to do outside the field, but I can't recall them) just sits in the Great Chain of In-Order-To. Whitehead is a human resource for tapping another resource that'll doubtlessly lead to some other damn resource, all endlessly interchangeable and replaceable.
I'll admit I haven't thought through this angle enough to produce a fully coherent reading, but I wanted to outline a few things and maybe return to it later. There's something here of a retrieval of the premodern, of marginal practices, as a form of resistance to modernity. In this period, of course, those practices weren't nearly as marginal.
A bit from an interview with Wheatley that I wanted to highlight:
"Magic became science, effectively," he says [...] "The Puritans were trying to iron paganism and magic out of Catholicism. Splitting up and melding ideas. There are two really important periods in British history where we actually made a difference to the world – the civil war and the industrial revolution – and I think at that moment in England, anything could have happened. Everyone was starving, and they were basically killing God, because they were killing the king, God's representative; they were writing their own rules. As O'Neil[l...] says, 'This country's at the edge of something, it could become anything.' That's what got us excited about the period. It's a time when people were thinking hard and radically."I hadn't read this before I started thinking about solve et coagula and focal/marginal practices and how they relate to the film, but I'm happy to see that "[s]plitting up and melding ideas" is mentioned by Wheatley. The survival of paganism into modernity is a central theme in folk horror, and what is paganism but a marginalized focal practice? The Wicker Man is famous for making its pagans seem sympathetic and reasonable for all their marginal, premodern practices.
There's something else here too, to the way mushrooms are used differently by O'Neill and Whitehead. For O'Neill, mushrooms are there to sedate labor into acquiescence. For Whitehead, mushrooms awaken. It's unclear whether O'Neill ever uses mushrooms himself. I think there's a case to be made that he hasn't, or at least not in sufficient quantities, given how Whitehead responds to them. My own reading is that the mushrooms are the treasure in the field, and O'Neill is oblivious to that potential awakening.
I'm leaving the ramble here, and I'll pick it up later. I'm just glad I managed to write something on this damn blog. Feel free to comment.
P. S. I ought to make something of the mushroom brew and how spagyrics in plant alchemy are the foundation for higher forms of alchemy such as mineral or animal.