Perpetual Stew

Question 1:

After a long day’s journey on your steed, you stop to enter the medieval inn at the entrance of a small village. You approach the counter where the innkeeper greets you. You order a room, a mead, and some food. Like modern fast-food fare, you don’t have to wait long for the sustenance: a bowl of steaming slop plops before you. 

Or, at least, imagine you’re watching a movie with this scenario.

Without electricity, microwaves, or assembly-line restaurants, how could a person whip up food so quickly in the days of yore? Hollywood convenience or historical possibility?

Question 2:

Most contemporary humans understand the mechanics of food and bacteria. You can’t leave most foodstuff out for long without the possibility of spoiling. Through hundreds of years of trial and error, we learned that cooking food helps to kill bad stuff, and cooling or freezing food helps keep the bad stuff from growing until we’re ready to eat. Many items can be stored frozen for long periods, perhaps indefinitely. How about the reverse? Could we heat something to the proper temperature to keep it safe indefinitely?

The answer to both questions can be illustrated by perpetual stew!

An imagined setting in a medieval inn

At the medieval inn, the nourishment you might have ingested would likely have arrived in the form of pottage or pot-au-feu. The former is a thick, boiled stew, while the latter is a mixture of broth and a boiled heap of veggies or meat. These recipes represent the technology of the time. Creativity and art were certainly afterthoughts in the era of pots and fire. Yet, they also offered a vital convenience. This fare could reduce the time needed to prepare and, given the proper fuel and upkeep, churn indefinitely.

Perpetual stews were also known as forever soup, a hunter’s pot, or a hunter’s stew. The basic gist is to take a pot, load it up with whatever food is at hand and some water, kickstart the fire, and let the stew simmer. When someone samples a bit of the savory broth, the chef tosses new food and liquid into the pot. The point is never to let the pot empty.

So, when a beleaguered traveler enters the inn, a bowl of stew can always be ready.

Root vegetables, tubers, cabbages, and available meats were common additions to perpetual stews. The modern germophobe might reel at the thought of eating something that had been cooking for weeks, months, or years. However, if the pot maintained the proper temperature, bacteria could not grow. Still, heat isn’t the only consideration when thinking about spoiling food. Bacteria also create waste toxins. If a lump of meat has gone bad, heating it to the point of killing the bacteria will not remove the leftover toxic matter. Suppose the pot is generally hot enough to keep bacteria from growing, but the integrity of the starting material is questionable or the heat is not constantly maintained. In that case, the toxic byproducts might amass in the stew. Yet, medieval people did not drop in massive numbers from eating this way. The changing nature of the perpetual stew was the key. Food exits, food enters, including any possibly nasty material. In most cases, this turnover must have been good enough to keep the buildup low.

This low-tech solution to the reality of the era simply worked. In southern France, a pot-au-feu reportedly simmered from the 15th century until World War II, when they ran out of ingredients thanks to German occupation. A restaurant in Normandy purportedly boasts a three-century perpetual stew.

Far from an ancient practice, many current restaurants and chefs utilize the technique. A restaurant in Bangkok serves soup that’s bubbled for nearly half a century. A chef in New York aimed to reduce waste by utilizing a perpetual stew to create broth for his restaurant. Why would today’s cooks want to go this route? Much like a coffee or wine blend, sometimes concoctions can taste delicious or unique when unexpected inputs meld.

A perpetual stew in Bangkok nearly 50 years old - photo by Annierau

Does perpetual stew change your outlook on the Ship of Theseus?

According to the Stanford Encyclopedia of Philosophy, the most popular resolution of the paradox is to assume that the material out of which the ship is constructed is not the same object as the ship, but that the two objects occupy the same space at the same time. In this theory, form and constitution differ. When parts are interchangeable, the materials can change but the ship-as-form remains.

Applying this logic to perpetual stew, the constituent ingredients can come and go but the burbling soup persists. So, if you sip the stew, you could be ingesting decades- or centuries-old food. One could argue the perpetual stew does not fit the Ship paradox because the constituent parts can differ. On the boat, atoms change but the form of the parts remains the same. Replacing carrots with potatoes would be akin to replacing a mast with a fishing rod. However, this viewpoint neglects the possibility of replacing functionally identical parts with different make-ups (e.g. switching out rotten teak for new oak). In the form-over-constitution argument, the boat-object-as-schematic matters most. Applying this thought to the stew inherently allows for different ingredients. The blueprint for the soup – what makes it perpetual, in this argument – is the recipe, which allows for flexibility. Therefore, in this paradigm, the perpetual soup in the cauldron would be considered the same object for its lifespan.

The Ship of Theseus might seem to be a theoretical exercise, but these everlasting soups display the idea exists in the physical realm. If a perpetual stew cooked in one pot since the 15th century, how many of the atoms of the original concoction might hide in the current-day broth? Would you want to eat a tuber molecule from the 1400s? If no ancient atoms remain, is it the same soup?

The next time you enjoy hotpot, perhaps ponder the nature of immortality, form, and identity. Or, forget about it all and enjoy the food.

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