I like to tell my students stories from the history of science. Not because they mysteriously boost student engagement. Not even because stories are “psychologically privileged” and might lead to greater retention. I tell them simply because I, presumably like all teachers, seek to foster a certain set of values and dispositions amongst my students. So, slowly, slowly, I tell them things which might help in the collective effort of inculcating those values. The below is one of my favourites and I came across it first in this book.

Mercury has long held a fascination within the realm of natural philosophy. Anyone who has witnessed it shining and shimmering as it rolls around on a surface will understand its allure (1). The early philosophers believed that it could somehow be utilised in the manufacture of a much-sought elixir which would guarantee eternal life.

In the 3rd Century CE the Chinese philosophers created such an elixir for the Emperor. Unfortunately, not knowing that mercury was toxic, the Emperor died after taking the elixir.

You would have thought that this would be the end of the experiment. Yet surprisingly, at least two subsequent emperors died in similar circumstances.

Surely it must have been obvious that instead of granting life, the elixir was taking it. So why did these hapless emperors continue down this deadly path?

When a human ingests a large dose of mercury, they die shortly after. But once they have passed on an amazing thing happens to their body. Mercury is toxic to humans, but it is also toxic to the bacteria which ordinarily would decompose the body. The corpse therefore “lives” for longer, it is preserved for a greater length of time than the corpse of one who did not ingest mercury.

The philosophers took this as sure sign that they were on the right track. True, they hadn’t quite got the formula right yet, but they were certain that mercury granted longevity – after all, just look at this corpse free of decay! We do not need a brand new formula, we just need to fiddle the recipe a bit – a little tweak here, a little tinker there.

I do not think you need me to elaborate much on the message of the story. But its relevance to teachers and students alike is clear. Our paradigms are hard to shift; they are built in to our psyches and we are hard-wired to seek their confirmation. But occasionally we need to try and transcend those biases and see that sometimes our past approaches and ways of thinking don’t need mere tweaking or tinkering. Sometimes, we need a brand new formula.



(1) When I was at school mercury was already banned for students to play with, but my understanding is that earlier generations were allowed much greater access. In Barcelona there is a museum of modern art in the home of Juan Miro where there is a beautiful water feature which uses mercury instead of water. It is absolutely stunning and if you are in that area well worth a trip to see.
NB this blog was partly inspired by Katherine Birbalsingh’s excellent blog on a similar theme.