The First Half-Million Words: Director's Commentary by seekeronthepath

In terms of your first question, I don’t remember confidently, but I think I did use chemotherapy as an inspiration. I certainly based it on something from actual medicine, just like the curse on Lockhart was based on hemochromatosis.

In terms of your last question…it’s complicated. I tend to use the nineteenth century as my baseline, but I vary it a lot, and that’s because we see it varied a lot in canon, and also because of how history works.

We can reasonably assume that at some point, there was no distinction between the muggle and wizarding world. We can also assume that the Statute of Secrecy defines a change that had already been happening, or it wouldn’t have been possible to implement. So by the late 17th century, the wizarding world was already mostly ‘hidden’. 

However, we see very clearly that post-17th century technologies continued to reach the wizarding world: notably steam trains, cameras, and elevators. We also see post-17th century social technologies, such as government administration run by ministers and departments, the use of imprisonment as punishment, and licenses for use of particular forms of transport. Fashion is distinctly different between the books and the movies: in the books, wizards clearly wear dress-like robes almost exclusively, while in the movies, what we see of wizarding fashion is a pastiche of modern, Edwardian, and robes over the top. From a Doylist perspective, it’s very clear that Rowling is not interested in history (see, for example, the entire phenomenon of Binns), and none of this can be taken as an intentional anchoring of her world in a particular time. From a Watsonian perspective, we have to conclude that there is at least some penetration of muggle ideas into the wizarding continuing through the nineteenth century, but that this is partial and also tends to lag.

(For those unfamiliar, ‘Doylist’ and ‘Watsonian’ are two levels of trying to analyse why things are the way they are in a story. The ‘Doylist’ perspective is equivalent to asking Arthur Conan Doyle why Sherlock Holmes did something: why did the author write it that way? The ‘Watsonian’ perspective is equivalent to asking John Watson why Sherlock Holmes did something: what is the in-universe reason why it happened that way?)

We actually see in the series an example of how muggle technologies cross the muggle/wizard barrier: Sirius’ motorcycle and Arthur’s car. They are clearly related projects, but are both the experiments of individual tinkerers. Nevertheless, the success of these two examples suggests that in another ten to thirty years, motor vehicles may be integrated into the wizarding world, as they become a reproducible technology. Note that in both cases, it’s clear that the wizards involved are making after-market modifications. While Sirius and Arthur may have needed a mechanic’s knowledge base to effectively work with the vehicles concerned, they did not need a car factory. It is likely that the steam trains we see entered the wizarding world in the same way: the steam engine was not designed independently, it was adopted from muggle designs, and probably purchased from muggle makers. With so few trains needed, the native ability to make them was probably never a priority; cameras were probably different.

So if that’s what happens with engineering, what about science? The two disciplines are deeply linked. Surely the adoption of nineteenth century technologies requires nineteenth century science to understand and run them?

Well, yes and no. Ultimately, science is a method for understanding how things work. And - this is important - your understanding can be wrong and still useful. For example, we know that in the late medieval period, bad smells were believed to cause or carry illness in some way. This led to projects to prevent standing, stagnant water in cities, and to a general practice of avoiding smelly water, improving ventilation in smelly places, and cleaning smelly objects. All of these would have helped reduce the transmission of disease. The understood mechanism was wrong, but because the practice had a noticeable effect, the theory was upheld.

Magical technologies (which is what spells are) do not rely on muggle science. They are frequently capable of things that muggle technologies can’t do, or historically couldn’t do until quite recently. Medically, for example, we see spells which seal wounds and erase bruises in moments, and potions which replenish lost blood. In that context, the canonical revulsion at the idea of stitches makes perfect sense: stitches are an ancient technology and have always carried an infection risk. If you can just seal over the wound, of course that’s better. Similarly, blood replenishing potions are a much lower risk alternative to blood transfusions - remember that it was only in the twentieth century that we understood and were able to test for blood type, so earlier blood transfusions had a random chance of killing you. If we assume that magical medicine as we see it in the 1990s is broadly similar to magical medicine as it existed in the 1940s, it was absolutely appropriate for wizarding doctors to more-or-less ignore muggle theory and technologies: they weren’t as good, and they weren’t as safe.

Furthermore, muggle scientific and medical development in the seventeenth, eighteenth, and nineteenth centuries, took place in exactly the contexts where we would expect wizards not to be: in muggle universities, and the social clubs of the muggle elite. While new technologies would have been visible to wizards out and about in the muggle world, muggle-born wizards were extracted from the education system that would have given them access to developing scientific theory. Visible medical practices, like the structure of a hospital and the existence of nurses, do get adopted by wizards in canon, but they stick to their own theoretical base.

Regarding my reference to the four humours: while we tend to think of the four humours as medieval, they only started to be replaced as the dominant medical theory in the 17th century, and weren’t really disproved until the mid-19th century. (And this was after almost two thousand years of being a major framework for medical theory.) So it makes sense that the idea might still be in use in the magical world. (Although we hope there is some awareness of germ theory, which replaced it, if only so that we can imagine all the doctors washing their hands regularly.)

All of this is really a justification for decisions I’ve already made. But you didn’t just ask for the justification; you wanted to know how I make the decision. Broadly, I start with what’s there: with any mentions in canon that seem relevant. Where we have details about a particular topic, what is their historical ‘vibe’? If we don’t have details, are there related topics where we have more clues? This usually leads me to a broadly nineteenth century base, trending later for legal, political, and engineering aspects, and earlier for medical, scientific, and scholarly aspects. And then I look for something cool in actual history that fits the vibe, and use that.